Engine P Code Lookup

Welcome to the P Code Lookup page. Let’s take a closer look at what aP Code is and what it means.
The P Code is 5 characters. It starts with a letter and then has 4 numbers following. That 5 character code then has a name that corresponds to each alpha-numeric code. So a standard p code will look like this:” P0455 evap system large leak detected.” The first character is the letter P. The P stands for powertrain and it will always be the first letter for any code that can turn your check engine light on. The second character is for generic or manufacturer specific. So a “0” means generic and a “1”, “2”, or “3” means it’s manufacturer specific. The third character defines what system is effected. In our example, the 4 means auxiliary emissions controls. The fourth and fifth characters are variable and they define which particular part of the system has a failure detected. Easy right? Don’t worry, we’re going to make it much easier to understand.
In 1996 the federal government regulated a large portion of the p codes that can turn your check engine light on. If the problem that causes the check engine light to turn on is emissions related, then it has to be the same p code for every manufacturer in America. That’s where the “0” for a genericP Code comes from. It means that it’s the sameP Code for all vehicles built from 1996 on. So if you have a 1996 Dodge Caravan with a cylinder 6 misfire or a 2014 BMW 3 series with the same problem, theP Code for both is exactly the same: P0306. The “1”, “2”, or “3” in the second character position is called manufacturer specific because those codes that begin with one of those 3 digits, generally apply to only that line of vehicle such as: Ford, Dodge, or Toyota.

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There are close to a thousand codes that can turn on the check engine light in any vehicle. We’re going to be describing the most common ones. Most vehicles will experience a misfire at some point in their lives, so a p code like “P0304 cylinder 4 misfire” is pretty common. A p code like this- “P2084 Exhaust Gas Temp Sensor Circuit Range/ Performance Bank1 Sensor 2″ (I promise that’s a thing) is much more rare because it only applies to vehicles that are built with that specific equipment.

 

Click here to see where you can get these codes read for you for FREE. If theP Code you’re searching for is not described in our list, or if you’ve found yourP Code and the info isn’t telling you everything you wanted to know, click here to contact our staff for further diagnostic assistance.

TheP Codes listed below will be broken down like this:

P Code and name
Brief explanation of the P Code and system it affects
Likelihood of the possible causes listed from most likely at the top, to least likely at the bottom
Best place to buy the parts

The section called “where to buy the parts” is there because so many people don’t understand that not all automotive parts are created equally. For example, if you buy an oxygen sensor from an aftermarket parts dealer and it doesn’t work, you can’t go and exchange it for a refund. This is true for almost any electrical part for your car, once you buy it and the package is opened, it’s yours for better or worse. So we’re going to advise you on where to buy the parts based on what’s going to be most cost effective for you. If you bought that oxygen sensor from an aftermarket parts dealer and it costs $90, and then it fails within 2 days, or doesn’t work correctly right away, you will need to buy another one. Some places will give you another one of the exact same sensor without charging you, but not all the time, and if the first one you bought failed, do you really want another one of the same sensors and to continue dealing with the headache of dealing with this malfunction? The oxygen sensor from the manufacturer may cost more, but it’s going to have the correct resistance built into it to make the electrical circuit function correctly. So we’ll advise you to buy the oxygen sensor from the manufacturer and in the long run it will save you, time, money, potential diagnostic fees, and just plain old headaches, when you get the correct parts you need the first time.

 

NOTE: When you get your vehicle scanned, you may find that the name of theP Code differs in several places that you can read the information. This is not a problem at all. The part that is absolutely the most important, is the actual alpha-numeric designation of the code. So P0306 is the most important part. Some scanners will call it “cylinder 6 misfire” others may call it something different. Even different sources to look up the P Code can have the names listed differently. The main thing to know is that as long as
you are reading about the correctP Code, you are following the correct diagnostics.
IMPORTANT WARNING: Before you attempt ANY repairs at all, always purchase a service manual for your vehicle and read any of the warnings it lists for the system you’re working with. Most people don’t really think about it, but your vehicle is very dangerous to work on. There are a multitude of ways to get burned, lose a finger, or even have a fatal accident if you’re not careful. So please always read your service manual for the system you’re working with and take every single precaution listed very seriously!!!!

 

NOTE: In the definitions listed below, there is a test drive recommended after you’ve completed any repairs to see if the condition is fixed. Before you take a test drive after a repair, always erase theP Code(s) first. This will turn the check engine light off and then you will know if the check engine light returns, you’ve got further diagnostics to complete

 




P0030- HO2S Heater Control Circuit Bank 1 Sensor 1

P0031- HO2S Heater Control Circuit Low Bank 1 Sensor 1

P0032- HO2S Heater Control Circuit High Bank 1 Sensor 1

The diagnostics for these 3P Codes are identical. Heater control circuit means a general circuit failure has been detected. Heater control circuit low means low voltage has been detected on the heater control circuit. Heater control circuit high means high voltage has been detected on the heater control circuit. You may get one or more of these codes at the same time for a single failure.

It might seem like a silly explanation, but an oxygen sensor (02) does exactly what it sounds like. It senses the oxygen content in the exhaust your engine creates. Some 02 sensors have a heater built into them. The heater is to get the sensor hot faster than the exhaust gasses are capable of. Getting the sensor hotter, faster, is a computer software strategy called, closed loop operation. The main thing that’s important to know about closed loop operation is that it makes your vehicle as fuel efficient as it can be. These 3 P Codes are to tell you there is a problem with the heater control part of the 02 sensor, or the part of the circuit that turns the 02 heater on. Since the heater is a part of the 02 sensor, the failure is likely to be the 02 sensor itself. There are other possible causes for this, but the sensor is the most common. In the interest of saving money changing the 02 sensor yourself is the most cost effective place to start. The rest of the code definition tells you which sensor to replace. Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or mounted into, the catalytic converter. If you happen to get any of these 3 P Codes in a 4 cylinder engine, this sensor will be the only one that’s in front of the catalytic converter. So find cylinder 1, follow the exhaust back from there, and the first 02 sensor you come across is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Erratic or slightly decreased fuel mileage
  • You won’t notice any other symptoms for this failure

Possible causes:

  • The oxygen sensor listed in the name of the P Code
  • A wiring issue between the ECM and the sensor itself. If you’ve replaced the sensor and this code returns, there’s likely to be a failure in the wiring system. At this point, I strongly recommend seeking out a qualified repair shop. Diagnosing wiring issues is very lengthy and technically difficult.
  • The ECM itself. This is another repair that I recommend taking to your repair shop. Most ECM’s will have to be programmed with the proper software to make it work with your vehicle. So taking it to a shop is really the only option available.

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0036- H02S Heater Control Circuit Bank 1 Sensor 2

P0037- H02S Heater Control Circuit Bank 1 Sensor 2

P0038- H02S Heater Control Circuit Bank 1 Sensor 2

The diagnostics for these 3 P Codes are identical. Heater control circuit means a general circuit failure has been detected. Heater control circuit low means low voltage has been detected on the heater control circuit. Heater control circuit high means high voltage has been detected on the heater control circuit. You may get one or more of these codes at the same time for a single failure.

This might seem like a silly explanation, but an (02) oxygen sensor does exactly what it sounds like. It senses the oxygen content in the exhaust your engine creates. Some 02 sensors have a heater built into them. The heater is to get the sensor hot faster than the exhaust gasses are capable of. Getting the sensor hotter, faster, is a computer software strategy called, closed loop operation. The main thing that’s important to know about closed loop operation is that it makes your vehicle as fuel efficient as it can be. These 3 P Codes are to tell you there is a problem with the heater control part of the 02 sensor, or the part of the circuit that turns the 02 heater on. Since the heater is a part of the 02 sensor, the failure is likely to be the 02 sensor itself. There are other possible causes for this, but the sensor is the most common. In the interest of saving money changing the 02 sensor yourself is the most cost effective place to start. The rest of the code definition tells you which sensor to replace. Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 2 indicates that it’s the 02 sensor behind the catalytic converter. If you happen to get any of these 3 P Codes in a 4 cylinder engine, this sensor will be the only one behind the catalytic converter. So find cylinder 1, follow the exhaust back from there, and the 02 sensor behind the converter for that side of the exhaust is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor! If you want to contact our certified technician with any questions about your check engine light or P codes, click here. It’s FREE!

Symptoms

  • Erratic or slightly decreased fuel mileage
  • You won’t notice any other symptoms for this failure

Possible causes:

  • The oxygen sensor listed in the name of the P Code:
  • A wiring issue between the ECM and the sensor itself. If you’ve replaced the sensor and this code returns, there’s likely to be a failure in the wiring system. At this point, I strongly recommend seeking out a qualified repair shop. Diagnosing wiring issues is very lengthy and technically difficult.
  • The ECM itself. This is another repair that I recommend taking to your repair shop. Most ECM’s will have to be programmed with the proper software to make it work with your vehicle. So taking it to a shop is really the only option available.

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0050- H02S Heater Control Circuit Bank 2 Sensor 1

P0051- H02S Heater Control Circuit Low Bank 2 Sensor 1

P0052- H02S Heater Control Circuit High Bank 2 Sensor 1

The diagnostics for these 3 P Codes are identical. Heater control circuit means a general circuit failure has been detected. Heater control circuit low means low voltage has been detected on the heater control circuit. Heater control circuit high means high voltage has been detected on the heater control circuit. You may get one or more of these codes at the same time for a single failure.

This might seem like a silly explanation, but an (02) oxygen sensor does exactly what it sounds like. It senses the oxygen content in the exhaust your engine creates. Some 02 sensors have a heater built into them. The heater is to get the sensor hot faster than the exhaust gasses are capable of. Getting the sensor hotter, faster, is a computer software strategy called, closed loop operation. The main thing that’s important to know about closed loop operation is that it makes your vehicle as fuel efficient as it can be. These 3 P Codes are to tell you there is a problem with the heater control part of the 02 sensor, or the part of the circuit that turns the 02 heater on. Since the heater is a part of the 02 sensor, the failure is likely to be the 02 sensor itself. There are other possible causes for this, but the sensor is the most common. In the interest of saving money changing the 02 sensor yourself is the most cost effective place to start. The rest of the p code definition tells you which sensor to replace. Bank 2 means that you have a V6 or V8 engine and bank 2 is the side of the engine where cylinder number 2 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or mounted into, the catalytic converter. So find cylinder 1, follow the exhaust back from there, and the first 02 sensor you come across is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Erratic or slightly decreased fuel mileage
  • You won’t notice any other symptoms for this failure

Possible causes:

  • The oxygen sensor listed in the name of the P Code:
  • A wiring issue between the ECM and the sensor itself. If you’ve replaced the sensor and this code returns, there’s likely to be a failure in the wiring system. At this point, I strongly recommend seeking out a qualified repair shop. Diagnosing wiring issues is very lengthy and technically difficult.
  • The ECM itself. This is another repair that I recommend taking to your repair shop. Most ECM’s will have to be programmed with the proper software to make it work with your vehicle. So taking it to a shop is really the only option available.

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0056- H02S Heater Control Circuit Bank 2 Sensor 2

P0057- H02S Heater Control Circuit Low Bank 2 Sensor 2

P0058- H02S Heater Control Circuit High Bank 2 Sensor 2

The diagnostics for these 3 P Codes are identical. Heater control circuit means a general circuit failure has been detected. Heater control circuit low means low voltage has been detected on the heater control circuit. Heater control circuit high means high voltage has been detected on the heater control circuit. You may get one or more of these codes at the same time for a single failure.

This might seem like a silly explanation, but an (02) oxygen sensor does exactly what it sounds like. It senses the oxygen content in the exhaust your engine creates. Some 02 sensors have a heater built into them. The heater is to get the sensor hot faster than the exhaust gasses are capable of. Getting the sensor hotter, faster, is a computer software strategy called, closed loop operation. The main thing that’s important to know about closed loop operation is that it makes your vehicle as fuel efficient as it can be. These 3 P Codes are to tell you there is a problem with the heater control part of the 02 sensor, or the part of the circuit that turns the 02 heater on. Since the heater is a part of the 02 sensor, the failure is likely to be the 02 sensor itself. There are other possible causes for this, but the sensor is the most common. In the interest of saving money changing the 02 sensor yourself is the most cost effective place to start. The rest of the p code definition tells you which sensor to replace. Bank 2 means that you have a V6 or V8 engine and bank 2 is the side of the engine where cylinder number 2 is located. Sensor 2 indicates that it’s the 02 sensor behind the catalytic converter. So find cylinder 2, follow the exhaust back from there, and the 02 sensor behind the converter for that side of the exhaust is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Erratic or slightly decreased fuel mileage
  • You won’t notice any other symptoms for this failure

Possible causes:

  • The oxygen sensor listed in the name of the P Code:
  • A wiring issue between the ECM and the sensor itself. If you’ve replaced the sensor and this code returns, there’s likely to be a failure in the wiring system. At this point, I strongly recommend seeking out a qualified repair shop. Diagnosing wiring issues is very lengthy and technically difficult.
  • The ECM itself. This is another repair that I recommend taking to your repair shop. Most ECM’s will have to be programmed with the proper software to make it work with your vehicle. So taking it to a shop is really the only option available.

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0068- MAP/MAF Throttle Position Sensor Correlation

An important first thing to know about this P Code is that your vehicle may not have a MAP and MAF sensor. It can have both or only one of them, so bear that in mind when you start looking for possible causes of this condition. This P Code is to let you know that the engine controller has sensed a disparity between how much air is entering the engine and how much it thinks should be entering the engine. Let me explain. The MAP stands for Manifold Absolute Pressure and the MAF stands for Mass Air Flow. These are 2 separate sensors that accomplish the same thing. Let’s look at the function of the MAP sensor first. This sensor measures the amount of air coming into the engine by sensing the pressure in the intake manifold. Think of your engine as a vacuum cleaner, when it’s running, it’s always drawing air in. There’s a restriction built into the air intake system called the throttle plate. When you put a restriction on a vacuum cleaner nozzle, you build up pressure behind it. When you suddenly open the restriction, the pressure drops down very low. So the MAP sensor measures the amount of pressure behind the restriction. It also has a barometer built into it so that it knows what the atmospheric pressure of the outside air is. It needs this information because it needs to know how thick the air is that’s entering the engine, to complete it’s pressure calculation. When the pressure is high, there’s low air flow into the engine. When the pressure is low, there is high air flow into the engine. The throttle plate (the restriction I mentioned earlier) has a sensor on it called, you guessed it, the Throttle Position Sensor or TPS. So when the TPS tells the engine computer that it’s open and allowing more air into the engine, the computer expects to see low manifold pressure. If it doesn’t see that low pressure it’ll set this P Code. Now we’ll take a look at the Mass Air Flow, or MAF, sensor. It tells the computer how much air is entering the engine in a much simpler fashion. It is placed directly into the air stream that enters the engine so that it can “feel” how much air flow there is. It feels this air flow by a small heated wire. The computer sends voltage to the wire inside of the sensor and it gets heated to a set temperature. When there is low air flow (throttle plate closed) the sensor stays at the same temperature it started out at. When there is high air flow (throttle plate open) the wire will cool down from the extra air. When the computer watches the TPS and sees that the throttle plate is open, it expects to see the wire for the mass air flow sensor cooling down. If it doesn’t see that, or it sees the wire cooling down when the throttle plate isn’t open, it’ll set this P Code. This code will also set if the MAP or MAF are telling the computer that there is low air flow but the throttle position sensor is saying that it’s open and should have high air flow. There is a good possibility that you will end up with other p codes when this one sets. It might only be one but, especially on newer cars, it could be several. So what to do about all of this? Always start off your diagnosis the same way every time: with the easiest solution possible. Drive your car and pay close attention to the way your engine is acting. Does it sound louder than normal? Does it seem like the engine is racing even when you’re not moving? Does it only seem to have a performance issue at a certain speed range? These are all going to be very important in narrowing down exactly what’s gone wrong with this system. First, since your engine is a big vacuum generator, does it have a vacuum leak? If there is a vacuum leak, it literally means your engine is drawing air from a source it shouldn’t be. Possible causes of a vacuum leak include: a loose vacuum hose, the air intake tube could be split or have a hole in it, one of the sensors that mount to the intake could be leaking or damaged. When looking for a vacuum leak just listen for your engine sucking air very loudly and follow it to the source, then repair whatever you find wrong when you get there. A scanner would be helpful in finding the source of this P Code, but we’re going to assume you don’t have access to one. In that case (and after you’ve thoroughly checked for vacuum leaks) it will be worth the money to seek out a local shop for diagnosis. Without a scanner and wiring testing equipment, you could end up replacing all 3 of these sensors and still not have found the problem. If the sensor(s) itself has a problem, most likely there will be an additional P Code. There are even more scenarios that can cause this code but they are basically all different aspects of the same condition. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Your engine runs rough. Whether it’s intermittent, or all the time, your engine won’t run smoothly
  • Lack of power/loss of power. You will notice this when you’re accelerating. It will feel like something is holding your engine back
  • High engine idle

Possible causes:

  • The most likely cause of this p code is a vacuum leak. Whether it’s on the intake side of the system or in the engine itself, this is the first thing to check
  • A faulty sensor. Remember to find out if your vehicle has both a MAP and a MAF sensor. All vehicles will have a TPS. Newer vehicles with an electronic throttle body will still have a TPS but it’s a part of the gas pedal assembly. If it’s a traditional throttle body assembly, the sensor will be mounted directly to the throttle body. Mounting locations for the MAP differ by manufacturer. The MAF will always be mounted to the air intake hose
  • After you’ve checked those two things first, the next level of possibility, is a wiring problem. Any of the sensors listed on this code could have a wiring issue. This is another condition that, if it exists, will almost definitely set more than one P Code. If there is a P Code for a circuit problem with any of the sensors listed, then that P Code should be diagnosed first.
  • The last possibility is the ECM. For these last two possibilities, you will want to seek your local repair shop. A wiring problem requires specialized equipment to accurately diagnose and the ECM has to be programmed when it’s replaced. The programming will have to be done by a shop that is licensed to download the software to program the ECM. A simple call will tell you whether or not the shop you’re considering, is able to do this repair

Where to buy the parts:

For any of the sensors, I recommend by them from the manufacturer. They are available from aftermarket parts dealers, but it’s best to use manufacturer parts for sensors. The fuel pump can be purchased from any of the aftermarket dealers. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0087- Fuel Rail/Fuel System Pressure Too Low

This P Code is pretty straight forward. There is a fuel pressure sensor mounted directly into the fuel rail and tells the ECM what the fuel pressure is that’s being delivered to the fuel injectors. The system has detected that the fuel pressure is lower than what it expects based on the fuel demand from the injectors. This P Code will often be accompanied by misfire and fuel system lean P     codes. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Your engine will run rough and could even stall when the throttle is released very quickly or when you come to a stop
  • Your vehicle could be running rich. When the engine runs too rich (too much fuel going into the combustion chamber) there can be a black, sooty smoke from the exhaust and you will smell fuel
  • Other P Codes which indicate fuel pump failure, fuel injector failure, or the rail sensor failure

Possible causes:

  • First the fuel pump should be inspected for failure. Since the pump is responsible for making the fuel pressure, it’s the most likely reason there is a lack of pressure
  • A blockage between the fuel pump and the fuel rail. The fuel filter is the first place to check for a blockage. If it’s been a long time since your fuel filter has been changed, start with that and then drive the vehicle to see if the problem still exists. If the fuel filter is ok, but a blockage is still suspected, check the fuel lines for being kinked or pinched. There is also a sock style filter on the bottom of the fuel pump. Check here for a blockage last because it’s the hardest part to physically check and because for that filter to be clogged, some foreign material would have to have gotten into the fuel tank
  • The fuel injectors should be checked for leaking. If the injector is leaking, it will almost definitely be only one injector that’s leaking, then this P Code will set because the fuel pressure will be bleeding off from the leak
  • Next would be to check the fuel pressure sensor. As I mentioned, it will be mounted directly into the fuel rail. If there is no physical damage to the sensor, you will need a scanner to check for the sensor voltage.
  • The circuitry for the fuel pump, fuel pressure sensor, and the fuel injectors. These conditions will all be accompanied by other P Codes
  • The ECM is the least likely possibility for this p code. If all other possibilities have been exhausted, then you will need to seek your local repair shop to have the ECM replaced because the new ECM has to be programmed with the correct software. The programming will have to be done by a shop that is licensed to download the software to program the ECM. A simple call will tell you whether or not the shop you’re considering, is able to do this repair

Where to buy the parts:

The sensor should be purchased from the manufacturer. It may be available from the aftermarket dealers for some engines, but quality can vary greatly from one aftermarket dealer to another. The fuel injectors for almost all vehicles are sold only through the manufacturer. The fuel pump can be purchased from any of the aftermarket parts dealers. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.






P0100- Mass or Volume Air Flow Circuit malfunction

P0101- Mass or Volume Air Flow Circuit Range/Performance

P0102- Mass or Volume Air Flow Circuit Low

P0103- Mass or Volume Air Flow Circuit High

P0104- Mass or Volume Air Flow Circuit Intermittent

These 5 P Codes all indicate the same failure and use the same diagnostics to resolve it. The only thing that changes between the P Codes is the specific way the failure was noticed by your ECM, or Engine Control Module

These P Codes are to tell you that the MAF, or Mass Air Flow sensor, circuit has detected a problem with the control side of the circuit. This is an electrical P Code, meaning that a problem has been detected with the electrical operation and/or control of the sensor. The circuit malfunction P Code just means that a general error has occurred on the circuit. The circuit range/performance P Code means that the circuit is being reported erratically. The circuit low P Code means that low voltage is being reported for the sensor. The circuit high P Code means that high voltage is being reported for the sensor. The circuit intermittent P Code means that there has been an error detected but not all the time, and not every time the engine has run. The first thing to check is the connector for the MAF sensor. Make sure it is plugged in the full way, if its plugged in the whole way then remove the connector and check for any corrosion or damage to the pins. If that looks ok then check the wires coming out of the back of the sensor connector. Check to make sure they’re all seated fully in the body of the connector and not cut or damaged in any way. If you find any problems with any of these, then repair and drive the vehicle to see if the condition comes back. If these are not the cause then check for a vacuum leak. A vacuum leak in your engine is normally very easy to detect. Just open the hood and listen to the engine running at idle. If there is a vacuum leak, you will hear a loud sucking noise. Follow that to the source and repair. If there are other P Codes present, then you will have to look at them all together, as they are most likely all related to the same problem. You may see a misfire P Code or a vacuum leak detected P Code. Those conditions will need to be fixed first. After those things have all been inspected and/or repaired and the problem still exists, you can try replacing the MAF sensor. After this repair has been made, if the condition is still present, its time to consult your local repair shop. You’ve exhausted all of the easy causes for this P Code and now are facing a wiring or computer issue (ECM). If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Your engine may be running rough or have an erratic idle
  • Poor fuel mileage
  • The vehicle may stall or have a lack of power on acceleration
  • In some vehicles, no observable symptoms will be noted
  • Hard to start or no starting at all. The engine will crank but not catch, or start and then stall very quickly

Possible causes:

  • Loose or damaged MAF sensor connector
  • Vacuum leak
  • In some cases a misfire can cause this P Code. Expect there to be misfire P Codes present for this
  • MAF sensor
  • Wiring issues
  • ECM internal failure

Where to buy the parts:

The MAF sensor can be purchased from an aftermarket source. Most aftermarket MAF sensors are very reliable and will definitely save you money over buying from the manufacturer. As always, if the ECM does end up being the cause of the condition, I strongly recommend buying it from the manufacturer


P0105- Manifold Absolue Pressure/Barometric Pressure Circuit Malfunction

P0106- Manifold Absolue Pressure/Barometric Pressure Circuit Range/Performance

P0107- Manifold Absolue Pressure/Barometric Pressure Circuit Low

P0108- Manifold Absolue Pressure/Barometric Pressure Circuit High

P0109- Manifold Absolue Pressure/Barometric Pressure Circuit Intermittent

These 5 P Codes all indicate the same failure and use the same diagnostics to resolve it. The only thing that changes between these P Codes is the specific way the failure was noticed by your ECM, or Engine Control Module

These P Codes are to tell you that the MAP, or Manifold Absolute Pressure sensor, circuit has detected a problem with the control side of the circuit. This is an electrical P Code, meaning that an electrical problem has been detected with the control and/or operation of the sensor. NOTE: The barometer is a part of the MAP sensor. It can not be diagnosed or replaced separately. The circuit malfunction P Code just means that a general error has occurred on the circuit. The circuit range/performance P Code means that the circuit is being reported erratically. The circuit low P Code means that low voltage is being reported for the sensor. The circuit high P Code means that high voltage is being reported for the sensor. The circuit intermittent P Code means that there has been an error detected but not all the time, and not every time the engine has run.The first thing to check is the connector for the MAP sensor. Make sure it is plugged in the full way, if its plugged in the whole way then remove the connector and check for any corrosion or damage to the pins. If that looks ok then check the wires coming out of the back of the sensor connector. Check to make sure they’re all seated fully in the body of the connector and not cut or damaged in any way. If you find any problems with any of these, then repair and drive the vehicle to see if the condition comes back. If these are not the cause then check for a vacuum leak. A vacuum leak in your engine is normally very easy to detect. Just open the hood and listen to the engine running at idle. If there is a vacuum leak, you will hear a loud sucking noise. Follow that to the source and repair. After all of these things have been inspected and/or repaired, the next step would be to replace the MAP sensor. The MAP sensor for most vehicles will be mounted directly to the intake manifold. In some rare cases, it can be an internal part of the ECM. For information on where the MAP sensor is located for your vehicle, click here, to contact our staff. After this repair has been made, if the condition is still present, its time to consult your local repair shop. You’ve exhausted all of the easy causes for this P Code and now are facing a wiring or computer issue (ECM). If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Your engine may be running rough or have an erratic idle
  • Poor fuel mileage
  • The vehicle may stall or have a lack of power on acceleration In some vehicles, no observable symptoms will be noted
  • Hard to start or no starting at all. The engine will crank but not catch, or start and then stall very quickly

Possible causes:

  • Loose or damaged MAF sensor connector
  • Vacuum leak
  • MAP sensor
  • Wiring for the MAP sensor circuit
  • ECM

Where to buy the parts:

The MAP sensor can be purchased from any aftermarket parts dealer. The quality of these aftermarket sensors is usually pretty reliable. As always, I strongly recommend you purchase the ECM from the manufacturer


P0110- Intake Air Temperature Circuit Malfunction

P0111- Intake Air Temperature Circuit Range/Performance

P0112- Intake Air Temperature Circuit Low

P0113- Intake Air Temperature Circuit High

P0114- Intake Air Temperature Circuit Intermittent

These 5 P Codes all indicate the same failure and use the same diagnostics to resolve it. The only thing that changes between the P Codes is the specific way the failure was noticed by your ECM, or Engine Control Module

These P Codes are to tell you that the Intake Air Temperature sensor circuit has detected a problem with the control side of the circuit. This is an electrical P Code, meaning that an electrical problem has been detected with the control and/or operation of the sensor. The circuit malfunction P Code just means that a general error has occurred on the circuit. The circuit range/performance P Code means that the circuit is being reported erratically. The circuit low P Code means that low voltage is being reported for the sensor. The circuit high P Code means that high voltage is being reported for the sensor. The circuit intermittent P Code means that there has been an error detected but not all the time, and not every time the engine has run. The first thing to check is the connector for the Intake Air Temperature sensor. Make sure it is plugged in the full way, if its plugged in the whole way then remove the connector and check for any corrosion or damage to the pins. If that looks ok then check the wires coming out of the back of the sensor connector. Check to make sure they’re all seated fully in the body of the connector and not cut or damaged in any way. If you find any problems with any of these, then repair and drive the vehicle to see if the condition comes back. Once the wiring and the connector have been inspected, replace the Intake Air Temperature sensor. If, after these inspections and repairs have been performed, you still have this condition, you will need to visit your local repair shop. At this point, you’re dealing with a wiring or computer issue (ECM). If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • It is very unlikely that there will be any observable symptoms at all. The one thing you may notice, would be slightly decreased fuel mileage

Possible causes:

  • Loose or damaged Intake Air Temperature sensor connector
  • Intake Air Temperature sensor
  • Wiring issues
  • ECM

Where to buy the parts:

The Intake Air Temperature sensor can be purchased from any aftermarket parts dealer. The quality of these aftermarket sensors is pretty reliable. As always, if the ECM needs to be replaced, I strongly recommend buying it from the manufacturer


P0115- Engine Coolant Temperature Sensor Circuit Malfunction

P0116- Engine Coolant Temperature Sensor Circuit Performance/Range

P0117- Engine Coolant Temperature Sensor Circuit Low

P0118- Engine Coolant Temperature Sensor Circuit High

P0119- Engine Coolant Temperature Sensor Circuit Intermittent

These 5 P Codes all indicate the same failure and use the same diagnostics to resolve it. The only thing that changes between the P Codes is the specific way the failure was noticed by your ECM, or Engine Control Module

These P Codes are to tell you that the Engine Coolant Temperature sensor circuit has detected a problem with the control side of the circuit. This is an electrical P Code, meaning that an electrical problem has been detected with the control and/or operation of the sensor. The circuit malfunction P Code just means that a general error has occurred on the circuit. The circuit range/performance P Code means that the circuit is being reported erratically. The circuit low P Code means that low voltage is being reported for the sensor. The circuit high P Code means that high voltage is being reported for the sensor. The circuit intermittent P Code means that there has been an error detected but not all the time, and not every time the engine has run. The first thing to check is the connector for the Intake Air Temperature sensor. NOTE: NEVER CHECK THE WIRING OF THE ENGINE COOLANT TEMPERATURE SENSOR WHEN THE VEHICLE IS HOT. THE VEHICLE NEEDS TO SIT, WITH THE HOOD OPEN, FOR A MINIMUM OF 2 HOURS BEFORE YOU PUT YOUR HANDS ANYWHERE NEAR THIS SENSOR!!! Make sure it is plugged in the full way, if its plugged in the whole way then remove the connector and check for any corrosion or damage to the pins. If that looks ok then check the wires coming out of the back of the sensor connector. Check to make sure they’re all seated fully in the body of the connector and not cut or damaged in any way. If you find any problems with any of these, then repair and drive the vehicle to see if the condition comes back. Once the wiring and the connector have been inspected, replace the Engine Coolant Temperature sensor. NOTE: when you remove the Engine Coolant Temperature sensor, there will be some coolant coming out. If, after these inspections and repairs have been performed, you still have this condition, you will need to visit your local repair shop. At this point, you’re dealing with a wiring or computer issue (ECM). If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The vehicle may exhibit poor fuel mileage. It may also run very rich (lots of black smoke coming from the exhaust) this last isn’t very likely but it could happen on some vehicles
  • The cooling fans may run too much or not at all depending on the way the failure is being reported
  • Many vehicles will have no observable symptoms at all

Possible causes:

  • Loose or damaged Engine Coolant Temperature sensor connector and the wiring directly near it. For this p code pay particular attention to the wiring near the sensor. The Engine Coolant Temperature sensor will be mounted directly into a part of the engine where it will be in the flow of the coolant, meaning it will be close to some very hot metal when the engine is at operating temperature. This constant heat can be the cause of many wiring issues for this sensor. The wires will come from the factory wrapped with electrical tape, but this doesn’t preclude a failure due to the extreme heat near the wiring
  • Engine Coolant Temperature sensor
  • Wiring issues (not directly near the sensor)
  • ECM

Where to buy the parts:

The Engine Coolant Temperature sensor can be bought at any local aftermarket parts dealer. The reliability for these sensors from the aftermarket is very reliable. As always, if the ECM needs to be replaced (highly unlikely for this condition, but not impossible) I strongly recommend buying it from the manufacturer


P0120- Throttle Position Sensor Circuit Malfunction

P0121- Throttle Position Sensor Circuit Range/Performance

P0122- Throttle Position Sensor Circuit Low

P0123- Throttle Position Sensor Circuit High

P0124- Throttle Position Sensor Circuit Intermittent

These 5 P Codes all indicate the same failure and use the same diagnostics to resolve it. The only thing that changes between the P Codes is the specific way the failure was noticed by your ECM, or Engine Control Module

These P Codes are to tell you that the Throttle Position sensor circuit has detected a problem with the control side of the circuit. This is an electrical P Code, meaning that an electrical problem has been detected with the control and/or operation of the sensor. The circuit malfunction P Code just means that a general error has occurred on the circuit. The circuit range/performance P Code means that the circuit is being reported erratically. The circuit low P Code means that low voltage is being reported for the sensor. The circuit high P Code means that high voltage is being reported for the sensor. The circuit intermittent P Code means that there has been an error detected but not all the time, and not every time the engine has run. The first thing to check is the connector for the Throttle Position sensor. Make sure it is plugged in the full way, if its plugged in the whole way then remove the connector and check for any corrosion or damage to the pins. If that looks ok then check the wires coming out of the back of the sensor connector. Check to make sure they’re all seated fully in the body of the connector and not cut or damaged in any way. If you find any problems with any of these, then repair and drive the vehicle to see if the condition comes back. Once the wiring and the connector have been inspected, replace the Throttle Position sensor. If, after these inspections and repairs have been performed, you still have this condition, you will need to visit your local repair shop. At this point, you’re dealing with a wiring or computer issue (ECM). If you want to contact our certified technician with any questions about your check engine light or P codes, click here. It’s FREE!

Symptoms:

  • Poor idle quality/engine possibly won’t idle by itself
  • Possible start and stall condition, although this isn’t too likely
  • You could experience a hesitation on acceleration. When this occurs it will be when you push the gas pedal to a certain point in it’s travel, the Throttle Position sensor has a “dead spot” internally at this part of the sensor, and it will momentarily lose the throttle position in the ECM, until the gas pedal is moved passed this spot or released enough to come back before this spot
  • Many vehicles will not have any observable symptoms at all

Possible causes:

  • Loose or damaged Throttle position sensor connector
  • Throttle Position sensor
  • Wiring issue
  • ECM

Where to buy the parts:

The Throttle Position sensor will be available from any local aftermarket parts dealer. However the quality of this particular sensor from the aftermarket parts store is notoriously poor. I recommend buying it from the manufacturer. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0128- Coolant Temperature Below Thermostat Regulating Temperature

This P Code is very simple. The ECM is constantly monitoring the engine temperature at all times that the key is on and/or the engine is running. This P Code will set when the ECM sees that the engine has been running for a set amount of time (the amount of time it takes can vary slightly for each manufacturer) and has not reached the full operating temperature. The ECM looks at the intake air temperature and the Engine Coolant Temperature itself. As the engine runs for a longer time, and the intake air heats up, the ECM will expect to see the Engine Coolant Temperature steadily climbing to operating range. When the engine stays at a lower temperature than the ECM wants to see based on these factors, it will set this P Code. Just in case, check the coolant level first on the off chance that the level is low and causing the low temperature (this is most likely to make the engine overheat, but in some rare cases, it can make the engine run too cool). Whether it’s stuck open or if it came apart entirely, the absolute most common cause for this is a defective thermostat. This the next place you should check for the source of the problem. WARNING: DO NOT ATTEMPT ANY COOLING SYSTEM REPAIRS ON AN ENGINE THAT HAS NOT SAT FOR AT LEAST 2 HOURS WITH THE HOOD OPEN. In some vehicles the thermostat can be moderately difficult to very difficult to replace, so bear this in mind before you begin taking your engine apart and potentially strand your source of transportation! Most of the time the thermostat will be easy to get to and replace, so after it’s been replaced, fresh coolant has been added to the system, and the air has been bled from the coolant, drive the vehicle to see if the condition persists. If the problem still exists, the next thing to check is the cooling fans. Simply start the engine, turn the A/C off, and pay attention to the cooling fans. If they run constantly and never turn off, that is the source of this P Code. If this is the cause that you find, it would be a good idea to visit your local repair shop at this point because this will mean that the fans are shorted somewhere and a short can be difficult to trace. Especially if you don’t have a scanner, voltmeter, and a test light. Next check the connectors for the intake air temperature and engine coolant temperature sensors. Once disconnected, check both of these connectors for any corrosion or damage. Look at the wires coming out of the connector and make sure they are fully seated in the body of the connector. If no issues are found in the wiring immediately near either of these sensors at this point it’s time to visit your local repair shop. The engine coolant temp sensor, intake air temp sensor, the ECM, and the wiring between them will be where the problem is located at and you will need some very expensive diagnostic tools to continue the diagnosis. A little good news for you though: 9 out of 10 times, this p code will be caused by the thermostat and you won’t need to go any further. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The engine temperature gauge will read low
  • There may be a slight decrease in fuel mileage. It may be so slight that you won’t even notice
  • It’s very likely that there won’t be any observable symptoms

Possible causes:

  • Thermostat
  • Low coolant
  • Cooling fans running continuously
  • Engine coolant temperature sensor
  • Intake air temperature sensor
  • Wiring issue
  • ECM

Where to buy the parts:

The thermostat is available at any of your local aftermarket parts dealers. The quality of these parts is perfectly reliable. The engine coolant temp and intake air temp sensors may be available from the aftermarket parts dealers for some vehicles and not others. The quality of these parts is not greatly reliable. If you end up needing either of these sensors, I recommend going to the manufacturer. As always, in the unlikely event that the ECM is the cause of this DTC, I strongly recommend buying from the manufacturer


P0130- O2 Sensor Circuit Malfunction Bank 1 Sensor 1

P0131- O2 Sensor Circuit Low Voltage Bank 1 Sensor 1

P0132- O2 Sensor Circuit High Voltage Bank 1 Sensor 1

The diagnostics for these 3 P Codes are identical. The circuit malfunction code means that a general error has been detected for the O2 sensor named in the P Code. The low voltage code means literally that the named O2 sensor is reporting voltage too low for too long. The high voltage code means the O2 sensor is reporting voltage too high for too long.

As I’ve mentioned, these 3 P Codes are essentially the same for the diagnostics. They’re all for the same sensor (Bank 1 Sensor 1), the only difference is the nature of the failure that’s been reported to the ECM. If you have one of these P Codes, the most cost effective thing to do is to replace the named O2 sensor first. Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or mounted into, the catalytic converter. If you happen to get any of these 3 P Codes in a 4 cylinder engine, this sensor will be the only one that’s in front of the catalytic converter. So find cylinder 1, follow the exhaust back from there, and the first 02 sensor you come across is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. Once the O2 sensor in question has been replaced, then drive the vehicle and see if the condition is fixed. If the problem still exists, it’s time to visit your local shop. The only other causes for these P Codes will be a wiring issue or the ECM. The wiring issue can be quite a lengthy diagnosis and the ECM will need to be programmed with the correct software, so you will need s repair shop for the correct tools to diagnose or replace and program either of these conditions. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • These P Codes will definitely effect your fuel economy. It might not be a huge amount if the problem is intermittent, but it will effect at least to a point
  • Your engine may run rough, misfire, or stumble. Especially if the failed O2 sensor is reading high voltage. This will make the engine run rich (too much fuel being delivered to the engine) and will cause a misfire
  • There could be black smoke coming from the exhaust. This is also a condition of the fuel-to-air mixture being too rich
  • The engine may stall. This will most likely occur when the throttle is suddenly released, or when you come to a stop with the vehicle still in gear
  • In some cases there will be no noticeable symptoms. This is pretty unlikely for this type of DTC

Possible causes:

  • The O2 sensor named in the P Code
  • An issue with the connector. As I mentioned, be sure to check for water intrusion and corrosion
  • A wiring issue in the immediate vicinity of the sensor/sensor connector. Especially since the O2 sensor is mounted in the exhaust, be sure non of the wiring has been melted to, or heat damaged by, the exhaust
  • An exhaust leak. If there is a hole in the exhaust, this can allow unintended oxygen to enter the exhaust stream and essentially confuse the O2 sensor. If there is an exhaust leak, it will be pretty easy to notice. It will be loud enough to notice even with the hood closed.
  • There could be a vacuum leak. If one of your symptoms is black smoke from the tail pipe, and/or the engine is misfiring with this P Code, then check for a vacuum leak. Start the engine and open the hood. If a vacuum leak is present, there will be a loud sucking noise that’s pretty easy to notice. Follow the noise to it’s source and repair whatever you find is causing the noise
  • Wiring issue between the sensor and the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0133- O2 Sensor Slow Response Bank 1 Sensor 1

P0139- O2 Sensor Slow Response Bank 1 Sensor 2

P0153- O2 Sensor Slow Response Bank 2 Sensor 1

P0159- O2 Sensor Slow Response Bank 2 Sensor 2

These 4 P Codes are the same thing. The only difference is the sensor, or sensor circuit, that’s reporting the error.

These 4 P Codes are all the exact same problem but a different sensor is reporting the error. A normally functioning O2 sensor switches it’s voltage very quickly back and forth from the high range of it’s voltage, to the low range of it’s voltage. When this P Code sets, it means the voltage for the named O2 sensor is switching very slowly or staying at a certain voltage for too long. If the voltage isn’t switching correctly, then the ECM can’t adjust the fuel-to-air mixture correctly. The most likely cause of these P Codes is the O2 sensor named in the P Code. So track down the O2 sensor named in the code like this: Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or mounted into, the catalytic converter. Bank 1 sensor 2 is the side of the engine where cylinder 1 is located and sensor 2 is the O2 sensor after the catalytic converter. Bank 2 Sensor 1 is the side of the engine where cylinder 2 is located and sensor 1 is the O2 sensor mounted in front of, or directly into, the catalytic converter. Bank 2 Sensor 2 is the side of the engine where cylinder 2 is located and sensor 2 is the O2 sensor after the catalytic converter for that side. Once you have found the sensor that is indicated in the name of the code, check inside the connector for any type of water intrusion or corrosion. Check the wiring near the connector for being melted to the exhaust, or possibly heat damaged by being too close to the exhaust. If none of these issues are found, then the most cost effective next step would be to replace the O2 sensor you’re working with. After replacing the O2 sensor, test drive the vehicle to see if the condition is still present. If the condition still exists, it’s time to find your local repair shop. The issue will be within the wiring from the O2 sensor named by the P Code to the ECM, or the ECM itself. It will be necessary to visit your local repair shop because the wiring diagnosis can be pretty lengthy and involves several specialized tools (meaning expensive) and the ECM needs to be programmed with the correct software in order to operate correctly. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Decreased or erratic fuel mileage
  • It is pretty likely for this p code that there will be no observable symptoms

Possible causes:

  • The O2 sensor named by the P Code
  • Water intrusion or corrosion in the connector of the O2 sensor
  • If there is a small exhaust leak, it could cause this DTC. It would be a very small exhaust leak though
  • Wiring issue from the O2 sensor to the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0134- O2 Sensor Circuit No Activity Detected Bank 1 Sensor 1

P0140- O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2

P0154- O2 Sensor Circuit No Activity Detected Bank 2 Sensor 1

P0160- O2 Sensor Circuit No Activity Detected Bank 2 Sensor 1

These 4 P Codes are the same thing. The only difference is the sensor, or sensor circuit, that’s reporting the error.

These 4 P Codes are all the exact same problem but a different sensor is reporting the error. A normally functioning O2 sensor switches it’s voltage very quickly back and forth from the high range of it’s voltage, to the low range of it’s voltage. When this P Code sets, it means the voltage for the named O2 sensor is staying at the same voltage (or possibly it’s moving but just barely). If the voltage isn’t switching correctly, then the ECM can’t adjust the fuel-to-air mixture correctly. The most likely cause of these P Codes is the O2 sensor named in the code. So track down the O2 sensor named in the code like this: Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or mounted into, the catalytic converter. Bank 1 sensor 2 is the side of the engine where cylinder 1 is located and sensor 2 is the O2 sensor after the catalytic converter. Bank 2 Sensor 1 is the side of the engine where cylinder 2 is located and sensor 1 is the O2 sensor mounted in front of, or directly into, the catalytic converter. Bank 2 Sensor 2 is the side of the engine where cylinder 2 is located and sensor 2 is the O2 sensor after the catalytic converter for that side. Once you have found the sensor that is indicated in the name of the P Code, check inside the connector for any type of water intrusion or corrosion. Check the wiring near the connector for being melted to the exhaust, or possibly heat damaged by being too close to the exhaust. If none of these issues are found, then the most cost effective next step would be to replace the O2 sensor you’re working with. After replacing the O2 sensor, test drive the vehicle to see if the condition is still present. If the condition still exists, it’s time to find your local repair shop. The issue will be within the wiring from the O2 sensor named by the P Code to the ECM, or the ECM itself. It will be necessary to visit your local repair shop because the wiring diagnosis can be pretty lengthy and involves several specialized tools (meaning expensive) and the ECM needs to be programmed with the correct software in order to operate correctly. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Decreased or erratic fuel mileage
  • It is pretty likely for this DTC that there will be no observable symptoms

Possible causes:

  • The O2 sensor named by the P Code
  • Water intrusion or corrosion in the connector of the O2 sensor
  • If there is a small exhaust leak, it could cause this DTC. It would be a very small exhaust leak though
  • Wiring issue from the O2 sensor to the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0135- O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1

P0141- O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 2

P0155- O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 1

P0161- O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 2

These 4 P Codes are the same thing. The only difference is the sensor, or sensor circuit, that’s reporting the error.

These 4 P Codes are all the exact same problem but a different sensor is reporting the error. A normally functioning O2 sensor switches it’s voltage very quickly back and forth from the high range of it’s voltage, to the low range of it’s voltage. When this P Code sets, it means that the ECM has noticed that the engine has reached operating temperature but the O2 Sensor named in the P Code has not begun switching it’s voltage back and forth. If the voltage isn’t switching correctly, then the ECM can’t adjust the fuel-to-air mixture correctly. The most likely cause of these P Codes is the O2 sensor named in the code. So track down the O2 sensor named in the code like this: Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or mounted into, the catalytic converter. Bank 1 sensor 2 is the side of the engine where cylinder 1 is located and sensor 2 is the O2 sensor after the catalytic converter. Bank 2 Sensor 1 is the side of the engine where cylinder 2 is located and sensor 1 is the O2 sensor mounted in front of, or directly into, the catalytic converter. Bank 2 Sensor 2 is the side of the engine where cylinder 2 is located and sensor 2 is the O2 sensor after the catalytic converter for that side. Once you have found the sensor that is indicated in the name of the code, check inside the connector for any type of water intrusion or corrosion. Check the wiring near the connector for being melted to the exhaust, or possibly heat damaged by being too close to the exhaust. If none of these issues are found, then the most cost effective next step would be to replace the O2 sensor you’re working with. After replacing the O2 sensor, test drive the vehicle to see if the condition is still present. If the condition still exists, it’s time to find your local repair shop. The issue will be within the wiring from the O2 sensor named by the P Code to the ECM, or the ECM itself. It will be necessary to visit your local repair shop because the wiring diagnosis can be pretty lengthy and involves several specialized tools (meaning expensive) and the ECM needs to be programmed with the correct software in order to operate correctly. If you want to contact our certified technician with any questions about your check engine light or P odes, click here. It’s FREE!

Symptoms:

  • The only symptom that you will likely notice for these P Codes is poorer than normal fuel mileage

Possible causes:

  • The O2 sensor named by the P Code
  • Water intrusion or corrosion in the connector of the O2 sensor
  • If there is a small exhaust leak, it could cause this DTC. It would be a very small exhaust leak though
  • Wiring issue from the O2 sensor to the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0136- O2 Sensor Circuit Malfunction Bank 1 Sensor 2

P0137- O2 Sensor Circuit Voltage Low Bank 1 Sensor 2

P0138- O2 Sensor Circuit Voltage High Bank 1 Sensor 2

The diagnostics for these 3 P Codes are identical. The circuit malfunction P Code means that a general error has been detected for the O2 sensor named in the P Code. The low voltage P Code means literally that the named O2 sensor is reporting voltage too low for too long. The high voltage P Code means the O2 sensor is reporting voltage too high for too long.

As I’ve mentioned, these 3 P Codes are essentially the same for the diagnostics. They’re all for the same sensor (Bank 1 Sensor 2), the only difference is the nature of the failure that’s been reported to the ECM. If you have one of these P Codes, the most cost effective thing to do is to replace the named O2 sensor first. Bank 1 means that you have a V6 or V8 engine and bank 1 is the side of the engine where cylinder number 1 is located. Sensor 2 indicates that it’s the 02 sensor after the catalytic converter. If you happen to get any of these 3 P Codes in a 4 cylinder engine, this sensor will be the only one that’s after the catalytic converter. So find cylinder 1, follow the exhaust back from there, and the last 02 sensor you come across, for this side of the exhaust, is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. Once the O2 sensor in question has been replaced, then drive the vehicle and see if the condition is fixed. If the problem still exists, it’s time to visit your local shop. The only other causes for these P Codes will be a wiring issue or the ECM. The wiring issue can be quite a lengthy diagnosis and the ECM will need to be programmed with the correct software, so you will need s repair shop for the correct tools to diagnose or replace and program either of these conditions. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • These P Codes will definitely effect your fuel economy. It might not be a huge amount if the problem is intermittent, but it will effect at least to a point
  • Your engine may run rough, misfire, or stumble. Especially if the failed O2 sensor is reading high voltage. This will make the engine run rich (too much fuel being delivered to the engine) and will cause a misfire
  • There could be black smoke coming from the exhaust. This is also a condition of the fuel-to-air mixture being too rich
  • The engine may stall. This will most likely occur when the throttle is suddenly released, or when you come to a stop with the vehicle still in gear
  • In some cases there will be no noticeable symptoms. This is pretty unlikely for this type of P Code

Possible causes:

  • The O2 sensor named in the P Code
  • An issue with the connector. As I mentioned, be sure to check for water intrusion and corrosion
  • A wiring issue in the immediate vicinity of the sensor/sensor connector. Especially since the O2 sensor is mounted in the exhaust, be sure non of the wiring has been melted to, or heat damaged by, the exhaust
  • An exhaust leak. If there is a hole in the exhaust, this can allow unintended oxygen to enter the exhaust stream and essentially confuse the O2 sensor. If there is an exhaust leak, it will be pretty easy to notice. It will be loud enough to notice even with the hood closed.
  • There could be a vacuum leak. If one of your symptoms is black smoke from the tail pipe, and/or the engine is misfiring with this DTC, then check for a vacuum leak. Start the engine and open the hood. If a vacuum leak is present, there will be a loud sucking noise that’s pretty easy to notice. Follow the noise to it’s source and repair whatever you find is causing the noise
  • Wiring issue between the sensor and the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0150- O2 Sensor Circuit Malfunction Bank 2 Sensor 1

P0151- O2 Sensor Circuit Voltage Low Bank 2 Sensor 1

P0152- O2 Sensor Circuit Voltage High Bank 2 Sensor 1

The diagnostics for these 3 P Codes are identical. The circuit malfunction code means that a general error has been detected for the O2 sensor named in the P Code. The low voltage code means literally that the named O2 sensor is reporting voltage too low for too long. The high voltage P Code means the O2 sensor is reporting voltage too high for too long.

As I’ve mentioned, these 3 P Codes are essentially the same for the diagnostics. They’re all for the same sensor (Bank 2 Sensor 1), the only difference is the nature of the failure that’s been reported to the ECM. If you have one of these P Codes, the most cost effective thing to do is to replace the named O2 sensor first. Bank 2 means that you have a V6 or V8 engine and bank 2 is the side of the engine where cylinder number 2 is located. Sensor 1 indicates that it’s the 02 sensor in front of, or directly mounted into, the catalytic converter. If you happen to get any of these 3 P Codes in a 4 cylinder engine, this sensor will be the only one that’s in front of, or directly mounted into, the catalytic converter. So find cylinder 2, follow the exhaust back from there, and the first 02 sensor you come across, for this side of the exhaust, is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. Once the O2 sensor in question has been replaced, then drive the vehicle and see if the condition is fixed. If the problem still exists, it’s time to visit your local shop. The only other causes for these DTC’s will be a wiring issue or the ECM. The wiring issue can be quite a lengthy diagnosis and the ECM will need to be programmed with the correct software, so you will need s repair shop for the correct tools to diagnose or replace and program either of these conditions. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • These P Codes will definitely effect your fuel economy. It might not be a huge amount if the problem is intermittent, but it will effect at least to a point
  • Your engine may run rough, misfire, or stumble. Especially if the failed O2 sensor is reading high voltage. This will make the engine run rich (too much fuel being delivered to the engine) and will cause a misfire
  • There could be black smoke coming from the exhaust. This is also a condition of the fuel-to-air mixture being too rich
  • The engine may stall. This will most likely occur when the throttle is suddenly released, or when you come to a stop with the vehicle still in gear
  • In some cases there will be no noticeable symptoms. This is pretty unlikely for this type of  P Code

Possible causes:

  • The O2 sensor named in the P Code
  • An issue with the connector. As I mentioned, be sure to check for water intrusion and corrosion
  • A wiring issue in the immediate vicinity of the sensor/sensor connector. Especially since the O2 sensor is mounted in the exhaust, be sure non of the wiring has been melted to, or heat damaged by, the exhaust
  • An exhaust leak. If there is a hole in the exhaust, this can allow unintended oxygen to enter the exhaust stream and essentially confuse the O2 sensor. If there is an exhaust leak, it will be pretty easy to notice. It will be loud enough to notice even with the hood closed.
  • There could be a vacuum leak. If one of your symptoms is black smoke from the tail pipe, and/or the engine is misfiring with this P Code, then check for a vacuum leak. Start the engine and open the hood. If a vacuum leak is present, there will be a loud sucking noise that’s pretty easy to notice. Follow the noise to it’s source and repair whatever you find is causing the noise
  • Wiring issue between the sensor and the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0156- O2 Sensor Circuit Malfunction Bank 2 Sensor 2

P0157- O2 Sensor Circuit Voltage High Bank 2 Sensor 2

P0158- O2 Sensor Circuit Voltage Low Bank 2 Sensor 2

The diagnostics for these 3 P Codes are identical. The circuit malfunction code means that a general error has been detected for the O2 sensor named in the P Code. The low voltage code means literally that the named O2 sensor is reporting voltage too low for too long. The high voltage P Code means the O2 sensor is reporting voltage too high for too long.

As I’ve mentioned, these 3 P Codes are essentially the same for the diagnostics. They’re all for the same sensor (Bank 2 Sensor 2), the only difference is the nature of the failure that’s been reported to the ECM. If you have one of these codes, the most cost effective thing to do is to replace the named O2 sensor first. Bank 2 means that you have a V6 or V8 engine and bank 2 is the side of the engine where cylinder number 2 is located. Sensor 2 indicates that it’s the 02 sensor after the catalytic converter. If you happen to get any of these 3 P Codes in a 4 cylinder engine, this sensor will be the only one that’s after the catalytic converter. So find cylinder 2, follow the exhaust back from there, and the last 02 sensor you come across, for this side of the exhaust, is the one you’re looking for. When replacing the O2 sensor, make sure to check the connector for any type of corrosion, water inside of the connector, or the wires very near to the connector being damaged, or pulled out of the body of the connector. If you find any issues with the wires or the connector itself, then repair that before replacing the sensor. Once the O2 sensor in question has been replaced, then drive the vehicle and see if the condition is fixed. If the problem still exists, it’s time to visit your local shop. The only other causes for these P Codes will be a wiring issue or the ECM. The wiring issue can be quite a lengthy diagnosis and the ECM will need to be programmed with the correct software, so you will need s repair shop for the correct tools to diagnose or replace and program either of these conditions. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • These P Codes will definitely effect your fuel economy. It might not be a huge amount if the problem is intermittent, but it will effect it at least to a point
  • Your engine may run rough, misfire, or stumble. Especially if the failed O2 sensor is reading high voltage. This will make the engine run rich (too much fuel being delivered to the engine) and will cause a misfire
  • There could be black smoke coming from the exhaust. This is also a condition of the fuel-to-air mixture being too rich
  • The engine may stall. This will most likely occur when the throttle is suddenly released, or when you come to a stop with the vehicle still in gear
  • In some cases there will be no noticeable symptoms. This is pretty unlikely for this type of P Code

Possible causes:

  • The O2 sensor named in the P Code
  • An issue with the connector. As I mentioned, be sure to check for water intrusion and corrosion
  • A wiring issue in the immediate vicinity of the sensor/sensor connector. Especially since the O2 sensor is mounted in the exhaust, be sure non of the wiring has been melted to, or heat damaged by, the exhaust
  • An exhaust leak. If there is a hole in the exhaust, this can allow unintended oxygen to enter the exhaust stream and essentially confuse the O2 sensor. If there is an exhaust leak, it will be pretty easy to notice. It will be loud enough to notice even with the hood closed.
  • There could be a vacuum leak. If one of your symptoms is black smoke from the tail pipe, and/or the engine is misfiring with this P Code, then check for a vacuum leak. Start the engine and open the hood. If a vacuum leak is present, there will be a loud sucking noise that’s pretty easy to notice. Follow the noise to it’s source and repair whatever you find is causing the noise
  • Wiring issue between the sensor and the ECM
  • ECM

Where to buy the parts:

When buying a replacement 02 sensor, it’s best to buy it from the manufacturer. Aftermarket 02 sensors are notorious for not having the correct resistance in their wiring for the vehicle’s electrical system to read it accurately. Once you buy a sensor of any kind and it’s been opened, all you can do is exchange it for another of the exact same sensor. No parts stores or parts departments at the dealer will refund money for a sensor that’s been used. As always, if the ECM requires replacement, I strongly recommend buying it from the manufacturer.


P0171- Fuel System Too Lean Bank 1

P0174- Fuel System Too Lean Bank 2

The Diagnostics for these 2 P Codes are the same. The only difference is which side of the engine is reporting a lean condition (not enough fuel being delivered to the engine). In fact, it’s somewhat likely that you will have both P Codes at the same time

These 2 P Codes mean that the upstream O2 sensor for Bank 1 or Bank 2 (the upstream sensor is the one mounted in front of, or directly into, the catalytic converter) is telling the ECM that there is too much oxygen in the exhaust gasses. When there is too much oxygen in the exhaust, this is called a lean condition. When there is a lean condition in your fuel system, you may notice a lack of power on acceleration, some light knocking or pinging from the engine (this is called a spark knock and is caused by not enough fuel being ignited in the combustion process), a rough idle, and possibly some stalling when the vehicle is at a stop. The stalling will usually be worse the hotter the temperature of the vehicle gets. The most likely cause of these P Codes is a vacuum leak in the intake system. This will put too much air into the combustion chamber. To find a vacuum leak is usually pretty simple. Start the engine, open the hood, and listen to the engine. If you hear a loud sucking noise, then follow the noise to the source and look for a vacuum hose that’s not connected or missing, an intake gasket that’s damaged or missing, or a hole in a vacuum hose. These are just a few examples of what you may encounter when you find the source of the vacuum leak. The next likely cause for this is going to be a weak fuel pump or clogged fuel filter. After the vacuum leak has been ruled out, replace the fuel filter and drive the vehicle to see if the condition still exists. Especially if it’s been a long time since your fuel filter has been replaced. If the fuel filter doesn’t fix the problem, I’d recommend visiting your local repair shop. The fuel pump is not easy to replace for most vehicles (you will have to remove the fuel tank to replace the pump). There are some vehicles that have a fuel pump access panel under the rear seat or in the trunk of the car. This will allow you to inspect/replace the fuel pump without removing the fuel tank. However, the fuel pump is usually a pretty expensive repair. You wouldn’t want to pay for this repair and find out the problem still exists! Instead at this point, I recommend going to your local repair shop and paying for the diagnosis. It will be more cost effective at this point, once the easy stuff has been ruled out. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Lack of power on acceleration
  • A rough idle or misfire at idle
  • Possible stalling. If the vehicle is stalling with this condition, it’ll be worse the hotter the engine gets
  • In some vehicles there will be no observable symptoms

Possible causes:

  • First and foremost is a vacuum leak
  • A clogged or dirty fuel filter
  • A faulty MAF (Mass Air Flow sensor) if this is the case, expect there to be other P Codes present
  • A weak fuel pump. Note: there is also a “sock” style filter on the bottom of the fuel pump. If this gets full of sediment, it will cause this P Code
  • It’s possible that a defective O2 sensor for the bank that sets the code can cause this. If this is the case, expect there to be at least one more P Code
  • An exhaust leak between the engine and the upstream O2 sensor. If there is an exhaust leak causing this condition, it will be noisy and easy to find
  • Clogged fuel injectors. This condition would require special tools to diagnose and would not be easy to accomplish at your home

Where to buy the parts:

Any of the sensors listed as a cause would be best to be purchased from the manufacturer. The quality of these sensors from the aftermarket parts dealers is somewhat unreliable. The fuel filter is available from any local aftermarket parts dealer and the quality is perfectly acceptable. The fuel pump is available from any local aftermarket parts dealer. The quality of this can vary but most of the time, it’s very reliable.


P0172- Fuel System Too Rich Bank 1

P0175- Fuel System Too Rich Bank 2

The Diagnostics for these 2 P Codes are the same. The only difference is which side of the engine is reporting a rich condition (too much fuel being delivered to the engine). In fact, it’s somewhat likely that you will have both P Codes at the same time

These 2 P Codes mean that the upstream O2 sensor for Bank 1 or Bank 2 (the upstream sensor is the one mounted in front of, or directly into, the catalytic converter) is telling the ECM that there is too much fuel in the exhaust gasses. When there is too much fuel in the exhaust, this is a rich condition. When there is a lean condition in your fuel system, you may notice a lack of power on acceleration, a misfire is almost certain to accompany a rich condition, a rough idle, and possibly a stalling condition. The stalling will be worse when the vehicle is at full operating temperature and is at a stop. There will almost definitely be additional DTC’s with either or both of these P Codes. The most common cause of this P Code is the MAF (Mass Air Flow sensor). This part can be fairly expensive to replace. Luckily the quality of the aftermarket MAF sensors is pretty reliable and significantly cheaper. If your vehicle is running rough and blowing black smoke, and either or both of these P Codes are the only P Codes to show up, I recommend replacing the MAF sensor first. Before replacing the sensor, do a quick check under the hood for a vacuum leak. To find a vacuum leak is usually pretty simple. Start the engine, open the hood, and listen to the engine. If you hear a loud sucking noise, then follow the noise to the source and look for a vacuum hose that’s not connected or missing, an intake gasket that’s damaged or missing, or a hole in a vacuum hose. These are just a few examples of what you may encounter when you find the source of the vacuum leak. After these 2 things have been checked and/or repaired, I strongly recommend a visit to your local repair shop. After these 2 things, the diagnosis gets significantly tougher to perform and all of it will require special tools to accomplish. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Lack of power on acceleration
  • A misfire while driving or at idle, or both
  • Stalling. This will usually get worse the hotter the engine is
  • In some extremely rare cases, there will be no observable symptoms

Possible causes:

  • MAF (Mass Air Flow sensor)
  • A vacuum leak in the intake system near the MAF
  • Engine mechanical failure
  • Defective O2 sensor
  • Defective fuel pressure regulator
  • Various other engine sensors or failures

Where to buy the parts:

The MAF sensor can be purchased at any local aftermarket parts dealer. The quality of this sensor can vary slightly from one dealer to the next, but overall the quality is fairly reliable. After this, I strongly recommend to take your vehicle to the local repair shop and let them finish the diagnosis. There are just too many variables to make this an easy fix at home.






P0200- Injector Circuit Malfunction

P0201- Injector Circuit Malfunction Cylinder 1

P0202- Injector Circuit Malfunction Cylinder 2

P0203- Injector Circuit Malfunction Cylinder 3

P0204- Injector Circuit Malfunction Cylinder 4

P0205- Injector Circuit Malfunction Cylinder 5

P0206- Injector Circuit Malfunction Cylinder 6

P0207- Injector Circuit Malfunction Cylinder 7

P0208- Injector Circuit Malfunction Cylinder 8

The diagnostics for these next 9 P Codes are exactly the same. The only difference between the P Codes is, which fuel injector the ECM is reporting the error for

The ECM controls the fuel injectors through a very simple circuit. All of the fuel injectors are supplied power through a shared voltage circuit. The ground circuit for each injector is separate and is controlled by a switch inside the ECM called a driver circuit. The ECM turns the driver off or on depending on the demand of the engine. If any part of this circuit malfunctions, one or more of these P Codes will set. You will definitely notice a change in the way the vehicle runs. Whichever circuit is malfunctioning, that cylinder will be misfiring, which will make the engine run rough whether you’re driving or sitting at a stop. If any of these P Codes set, you will also most likely have a P Codes for a misfire on whichever cylinder the injector is malfunctioning. If you get one of these injector malfunction P Codes, try flushing the injectors first. A lot of people assume that a fuel injector flush is just something that their mechanic is trying to sell them to make money on. However, there is a legitimate use for an injector flush. This is the type of scenario that you will want to try the flush for. You can get a bottle of injector flush from any local aftermarket parts dealer for a pretty reasonable price. Make sure you follow the directions exactly as they are described on the back of the package. This may be enough to clean out the blockage, but it may not be. If not, then you will want to visit your local repair shop at this point. It takes several specialized tools to properly diagnose a bad injector, the wiring from the injectors to the ECM, or the ECM itself. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • You will notice a definite engine misfire
  • You will notice a decrease in fuel mileage, but the misfire will be the major symptom
  • Poor acceleration

Possible causes:

  • A bad fuel injector is the most likely cause for this P Codes. I would recommend flushing the injectors first, but the injector that’s named in the P Codes will likely still need to be replaced
  • Wiring between the injectors and the ECM
  • ECM

Where to buy the parts:

You can get a bottle of injector flush from any local aftermarket parts dealer for a pretty reasonable price. Make sure you follow the directions exactly as they are described on the back of the package. Ask the parts counter person for which brand of injector flush that works the best. Fuel injectors are not usually sold at the aftermarket parts dealers for most vehicles. As always, I strongly recommend you purchase the ECM from the manufacturer


P0217- Engine Over Temp Condition

This P Codes is pretty straight forward. It literally means what it says, your engine is running too hot. It might not be all the way to the top of the gauge, but it’s consistently too hot. There is no one main cause for this P Codes. You will want to start with the easiest things to check first. Check the level of the coolant in the coolant bottle and the radiator. NOTE: NEVER CHECK THE COOLANT IN THE BOTTLE OR THE RADIATOR WHEN THE VEHICLE IS HOT. THE VEHICLE NEEDS TO SIT, WITH THE HOOD OPEN, FOR A MINIMUM OF 2 HOURS BEFORE YOU PUT YOUR HANDS ANYWHERE NEAR THIS SYSTEM!!! While checking the level of the coolant, make sure to pay attention to the appearance of it as well. If the coolant is milky looking, you have a bigger problem on your hands. The head gasket could be blown and mixing engine oil into the coolant, or the transmission cooler may have ruptured and is mixing transmission fluid with the coolant. Either way, if the coolant appears milky, it’s time to visit your local repair shop, because there are major repairs needed at this point. If the coolant is low, then check all around the engine to see if there are any leaks. If so repair the leak you find, fill the system with coolant, and bleed all the air from the system. Drive the vehicle and see if the problem still exists. If the problem persists, or there were no leaks found, check the cooling fans. Just start the engine, turn the A/C off, and watch the cooling fans. If they don’t come on after 20 minutes or so (remember you should always start coolant system diagnosis with the vehicle cold), you need to diagnose the circuits for the fans. This is something you will most likely need to visit your local repair shop for. You could replace the fans without diagnosing them, but the fan motors are not very cheap, and it would be a waste to replace them only to find out there is a wiring problem with the fan control system. If the fans are working correctly, and the coolant isn’t low or in bad condition, the next item to check is the thermostat. The thermostat is very cheap and readily available at any aftermarket parts dealer. After these things have all been checked, it’s time to visit your local repair shop. The remaining causes for this P Codes will require special tools to diagnose and repair. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The first symptom you will notice is the temperature gauge on your dash indicating that the vehicle is running hot
  • In the event that the vehicle overheats badly, the coolant will be expelled from the coolant bottle under the hood. This can be confused as a leak. If the coolant is not coming from anywhere else but the bottle, don’t suspect a leak. Instead check the fans, thermostat, and lastly an internal engine malfunction
  • Poor fuel mileage
  • A bad smell due to the coolant being expelled from the engine

Possible causes:

  • Low coolant
  • A stuck thermostat
  • Malfunctioning cooling fan circuits or the fans themselves
  • Defective engine coolant temperature sensor
  • Internal engine failure. If this is the case, there is likely to be other DTC’s present
  • Defective water pump. This is usually accompanied by a leak but not always. Signs of a worn water pump, are a bearing noise or the vehicle only overheats while driving and cools down again while siting still

Where to buy the parts:

Any of the components that can cause a leak (any coolant hose, the radiator, the water pump, engine gaskets that seal the passages of the cooling system) can be purchased from your local aftermarket parts dealer. Cooling fans can be purchased through the aftermarket but the quality can vary greatly from one dealer to the other, depending on where they get their parts from.


P0230- Fuel Pump Primary Circuit Malfunction

This P Code is all electrical. If this P Code shows up, you need to visit your local repair shop. Unfortunately, there’s not even anything to check first for yourself. It will be a problem with the ECM, the fuel pump relay, or the wiring between these 2 pieces, and then the wiring on to the fuel pump itself. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • No start. This condition may be intermittent or it may just not start at all
  • Engine misfire
  • Lack of power on acceleration

Possible causes:

  • The fuel pump relay
  • The wiring from the ECM to the fuel pump relay
  • The wiring from the fuel pump relay to the fuel pump
  • The ECM

Where to buy the parts:

The only parts to really be replaced for this DTC are the fuel pump relay or the ECM. If the fuel pump relay needs to be replaced, it can easily be obtained from your local aftermarket parts dealer. The quality of aftermarket relays is perfectly reliable. As always, I strongly recommend you purchase the ECM from the manufacturer


P0231- Fuel Pump Secondary Circuit Voltage Low

P0232- Fuel Pump Secondary Circuit Voltage High

The diagnostics for these 2 P Codes are the same. The only difference between these 2 P Codes is that one sets a circuit failure for high voltage and one sets a circuit failure for low voltage

These P Codes are all electrical. If these P Codes show up, you need to visit your local repair shop. Unfortunately, there’s not even anything to check first for yourself. It will be a problem with the ECM, the fuel pump relay, or the wiring between these 2 pieces, and then the wiring on to the fuel pump itself. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • No start. This condition may be intermittent or it may just not start at all

Possible causes:

  • The fuel pump relay
  • The wiring from the ECM to the fuel pump relay
  • The wiring from the fuel pump relay to the fuel pump
  • The ECM

Where to buy the parts:

The only parts to really be replaced for these P Codes are the fuel pump relay or the ECM. If the fuel pump relay needs to be replaced, it can easily be obtained from your local aftermarket parts dealer. The quality of aftermarket relays is perfectly reliable. As always, I strongly recommend you purchase the ECM from the manufacturer


P0261- Cylinder 1 Injector Circuit Low

P0264- Cylinder 2 Injector Circuit Low

P0267- Cylinder 3 Injector Circuit Low

P0270- Cylinder 4 Injector Circuit Low

P0273- Cylinder 5 Injector Circuit Low

P0276- Cylinder 6 Injector Circuit Low

P0279- Cylinder 7 Injector Circuit Low

P0282- Cylinder 8 Injector Circuit Low

The diagnostics for these next 8 P Codes are the same. The only difference is which injector is reporting the error

These P Codes are all electrical in nature. You may have more than one of these show up at the same time. The P Code means that the injector control circuit has too low of voltage on a consistent basis. Most likely the cause of the low voltage will be the wiring between the ECM and the fuel injector that’s named in the code. It can also be the fuel injector itself or the ECM. In any of these cases, it’s time to visit your local repair shop. These failures will require special tools to diagnose and/or repair. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be a misfire for whichever cylinder is reporting the injector failure. There will most likely be a misfire P Code for this cylinder as well
  • If enough of the injector circuits malfunction at the same time, there will be a no start or extended crank time to start. If this is the case, suspect a cut in the wiring somewhere between the injectors and the ECM

Possible causes:

  • The wiring between the fuel injector and the ECM
  • The fuel injector itself
  • The ECM

Where to buy the parts:

The only parts to be replaced for these DTC’s will be the fuel injector or the ECM. It’s not likely that parts will need to be replaced for this DTC, it’s usually a wiring issue. If either of these parts does need to be replaced, the fuel injectors for most vehicles can not be bought from an aftermarket parts dealer. As always, I strongly recommend you purchase the ECM from the manufacturer


P0262- Cylinder 1 Injector Circuit High

P0265- Cylinder 2 Injector Circuit High

P0268- Cylinder 3 Injector Circuit High

P0271- Cylinder 4 Injector Circuit High

P0274- Cylinder 5 Injector Circuit High

P0277- Cylinder 6 Injector Circuit High

P0280- Cylinder 7 Injector Circuit High

P0283- Cylinder 8 Injector Circuit High

The diagnostics for these next 8 P Codes are the same. The only difference is which injector is reporting the error

These P Codes are all electrical in nature. You may have more than one of these show up at the same time. The P Code means that the injector control circuit has too high of voltage on a consistent basis. Most likely the cause of the high voltage will be the wiring between the ECM and the fuel injector that’s named in the P Code. It can also be the fuel injector itself or the ECM. In any of these cases, it’s time to visit your local repair shop. These failures will require special tools to diagnose and/or repair. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be a misfire for whichever cylinder is reporting the injector failure. There will most likely be a misfire P Code for this cylinder as well
  • If enough of the injector circuits malfunction at the same time, there will be a no start or extended crank time to start. If this is the case, suspect a cut in the wiring somewhere between the injectors and the ECM

Possible causes:

  • The wiring between the fuel injector and the ECM
  • The fuel injector itself
  • The ECM

Where to buy the parts:

The only parts to be replaced for these P Codes will be the fuel injector or the ECM. It’s not likely that parts will need to be replaced for this P Code, it’s usually a wiring issue. If either of these parts does need to be replaced, the fuel injectors for most vehicles can not be bought from an aftermarket parts dealer. As always, I strongly recommend you purchase the ECM from the manufacturer





P0300- Multiple Cylinder Misfire

P0301- Cylinder 1 Misfire

P0302- Cylinder 2 Misfire

P0303- Cylinder 3 Misfire

P0304- Cylinder 4 Misfire

P0305- Cylinder 5 Misfire

P0306- Cylinder 6 Misfire

P0307- Cylinder 7 Misfire

P0308- Cylinder 8 Misfire

The diagnostics for these 9 P Codes are the same. The only difference between the P Codes is which cylinder that reports the error.

All 9 of these P Codes report the exact same error. The ECM constantly monitors the speed of your engine as it runs. It does this with a crankshaft position sensor. It also uses a camshaft position sensor, but not to monitor engine speed specifically. When the ECM notices that one or more of the cylinders is moving at a different speed than the rest it starts a misfire monitor. Once it has determined that a cylinder has at least a 2% variance in speed from the rest a misfire P Code will be set for that cylinder. If the ECM determines that the variance is 10% or more, it will set a misfire P Code for that cylinder, but it will also make the check engine light flash. When your check engine light is flashing, your ECM is telling you that there is damage being done to your catalytic converter and the problem needs to be addressed as immediately as possible. So to start with, it’s important to see how many P Codes are present. If you have misfire P Codes present with a P Code for the crankshaft position sensor, then the crankshaft position sensor needs to be diagnosed first, because it will cause the other P Codes to appear. This is just one example of many possible scenarios, the principle of the example is what’s important: if you have misfire P Codes present and additional P Codes for something that can cause a misfire, that needs to be inspected first. If you have only the misfire P Codes then the first place to start is always with your spark system. Check the spark plugs first. Every internal combustion engine on the road has spark plugs. Check down the sides of the plugs, along the porcelain, to see if there are any signs of blackness. If you see this down the side of the spark plugs, there are minute cracks in the porcelain and that plug is “leaking” the spark out, causing your misfire. If no black marks are noticed, then check the gap at the end of the plug for the proper width. As your spark plugs wear, this gap will increase in width, making it more likely that the plug will misfire. Next check the spark plug wires if your vehicle is equipped with them. Look at the length of the wire from the spark plug to the distributor cap. If you see a whitish colored spot along the length of the wire anywhere, this is a spot that this wire is “leaking” the spark out. If no problems are found with plugs or wires, then look at the distributor cap. Remove the cap and look underneath. You will see small metal tabs or points here. If there is any buildup on them at all this corrosion will easily cause a misfire. The same goes for the rotor that sits under the distributor cap, any buildup or corrosion will cause a misfire. Not all vehicles have spark plug wires. Some vehicles have separate ignition coils for each cylinder. The tube that comes from the coil down to the plug is the same thing as a spark plug wire, it’s just a lot shorter and can’t be replaced separately. If you see any whitish spots on the outside of this tube, then that will cause a misfire, and that coil must be replaced. These are all visible signs that will indicate a misfire with the separate pieces of your spark system. My advice would be, if you have a misfire P Code present, start by giving your vehicle a good tune up. Especially if you have a good amount of miles on the odometer and it’s been a while since a tune up was done. A standard tune up consists of spark plugs, spark plug wires, distributor cap, and rotor. If your vehicle is one of the ones that has a separate coil for each cylinder, don’t replace all the coils as part of your tune up. This will be extremely expensive and unnecessary, just replace the spark plugs themselves. The spark system is the main cause of the majority of misfires and is a relatively easy fix. One piece of advice for those of you who are going to do a tune up on your own vehicle: if your engine has spark plug wires and a distributor cap, replace each spark plug wire one at a time. Do not take all the wires off of the distributor cap and then just start replacing them. Each cylinder has a wire that goes to a specific spot on the cap. If the wire is put in the wrong place, your engine will not run right. Once you have done a good tune up, drive the vehicle and see if the P Code returns. If the problem still exists, you will want to visit your local repair shop at this point. The remaining causes get harder and harder to diagnose after the tune up has been done. The fuel pump, crankshaft position and camshaft position sensors, any of the oxygen sensors, any of the fuel injectors, the mass airflow or manifold absolute pressure sensors, a fuel pressure regulator, an engine overheating condition, internal engine damage, or the ECM itself could all be the potential cause of a misfire. If there are P Codes in the ECM that are indicating any of these other sensors, be sure to start with them in your diagnosis first. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Running rough at idle or while driving
  • Loss of power
  • The engine is hard to start
  • Significantly reduced fuel mileage
  • Possible black smoke coming from the exhaust (this means the engine is running rich)
  • In some extremely rare cases, there will be no observable symptoms

Possible causes:

  • Spark plugs
  • Spark plug wires, distributor cap, and rotor
  • Spark coil or individual coil for the cylinder reporting the code
  • Fuel pump/fuel pressure regulator
  • Crankshaft or camshaft position sensors
  • Oxygen sensors
  • Mass air flow or manifold absolute pressure sensors
  • Fuel injectors
  • Engine overheating condition
  • ECM

Where to buy the parts:

The parts you need to do a basic tune up are readily available from your local aftermarket parts dealer. The lone caution I have for buying these parts from there is the spark plugs. Don’t be fooled into buying the spark plugs that have 2 or more electrodes, and don’t buy the absolute cheapest spark plugs available for your engine. Either of these 2 possibilities will cause more problems than they fix. Buy the spark plugs that are recommended for your specific engine. Other than that, the reliability for these parts from the aftermarket dealers is perfectly reliable. Any of the other parts that may be causing your misfire will have to be addressed as needed. If it’s a sensor causing your misfire then the manufacturer is the best bet for reliable parts. Fuel injectors are mostly only available from the manufacturer. Even if they are available from the aftermarket dealer, I would still recommend the manufacturer to purchase them. If you need gaskets or seals to fix a vacuum leak or compression leak in the engine, these parts are perfectly reliable from the aftermarket dealer. As always, I strongly recommend you purchase the ECM from the manufacturer


P0325- Knock Sensor 1 Circuit Malfunction Bank 1 or Single Sensor

P0326- Knock Sensor 1 Circuit Range/Performance Bank 1 or Single Sensor

P0327- Knock Sensor 1 Circuit Low Input Bank 1 or Single Sensor

P0328- Knock Sensor 1 Circuit High Input Bank 1 or Single Sensor

The diagnostics for these 4 P Codes are the same. The circuit malfunction P Code means that a general error has been detected. The range/performance P Code means that an error has been noticed over the operational range of the sensor. The low input P Code means that too low of a voltage is being reported and the high input P Code means that too high of a voltage is being reported.

These P Codes all mean the same thing. The difference is in the nature of the error being reported, but all deal with the same sensor, which is the knock sensor. Bank 1 means that this is the sensor for the side of the engine where cylinder 1 is located. The knock sensor does what it sounds like. It tells the ECM that your engine is knocking, which could potentially cause engine damage if it continues. The ECM uses this information to change the engine timing and stop the knocking. Unfortunately, most modern vehicles have the knock sensor underneath the intake manifold between the cylinder heads. This will not be easy to get to for diagnosis or replacement. If your knock sensor is mounted externally then the first thing to do is inspect the connector to see if there is any damage or corrosion inside the connector for the sensor. If there are no signs of a problem within the connector, then look at the wiring in the immediate vicinity of the sensor and connector. Once you have checked these things, if no problems are noted, replace the knock sensor itself, test drive the vehicle and see if the condition still exists. NOTE: if your vehicle has an overheating condition, this code could come up as a side effect. If the condition is still present after the replacement of the knock sensor, you will need to visit your local repair shop. The remaining causes will require special tools to diagnose and repair. Also if your knock sensor is not mounted externally, you will need to visit the repair shop first. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Engine pinging on acceleration
  • Possible RPM fluctuation
  • Engine may be running hotter or colder than normal
  • It’s possible there will be no observable symptoms

Possible causes:

  • Knock sensor
  • Wiring between the knock sensor and the ECM
  • ECM

Where to buy the parts:

The knock sensor is best purchased from the manufacturer. It has to have a very exact calibration to operate correctly so the sensors made with the manufacturer specs are the best for this sensor. As always, I strongly recommend you purchase the ECM from the manufacturer


P0330- Knock Sensor 1 Circuit Malfunction Bank 2

P0331- Knock Sensor 1 Circuit Range/Performance Bank 2

P0332- Knock Sensor 1 Circuit Low Input Bank 2

P0333- Knock Sensor 1 Circuit High Input Bank 2

The diagnostics for these 4 P Codes are the same. The circuit malfunction code means that a general error has been detected. The range/performance P Code means that an erratic error has been reported. The low input P Code means that too low of a voltage is being reported and the high input P Code means that too high of a voltage is being reported.

These P Codes all mean the same thing. The difference is in the nature of the error being reported, but all deal with the same sensor, which is the knock sensor. Bank 2 means that this is the sensor for the side of the engine where cylinder 2 is located. The knock sensor does what it sounds like. It tells the ECM that your engine is knocking, which could potentially cause engine damage if it continues. The ECM uses this information to change the engine timing and stop the knocking. Unfortunately, most modern vehicles have the knock sensor underneath the intake manifold between the cylinder heads. This will not be easy to get to for diagnosis or replacement. If your knock sensor is mounted externally then the first thing to do is inspect the connector to see if there is any damage or corrosion inside the connector for the sensor. If there are no signs of a problem within the connector, then look at the wiring in the immediate vicinity of the sensor and connector. Once you have checked these things, if no problems are noted, replace the knock sensor itself, test drive the vehicle and see if the condition still exists. NOTE: if your vehicle has an overheating condition, this code could come up as a side effect. If the condition is still present after the replacement of the knock sensor, you will need to visit your local repair shop. The remaining causes will require special tools to diagnose and repair. Also if your knock sensor is not mounted externally, you will need to visit the repair shop first. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Engine pinging on acceleration
  • Possible RPM fluctuation
  • Engine may be running hotter or colder than normal
  • It’s possible there will be no observable symptoms

Possible causes:

  • Knock sensor
  • Wiring between the knock sensor and the ECM
  • ECM

Where to buy the parts:

The knock sensor is best purchased from the manufacturer. It has to have a very exact calibration to operate correctly so the sensors made with the manufacturer specs are the best for this. As always, I strongly recommend you purchase the ECM from the manufacturer


P0335- Crankshaft Position Sensor “A” Circuit Malfunction

P0336- Crankshaft Position Sensor “A” Circuit Range/Performance

P0337- Crankshaft Position Sensor “A” Circuit Low

P0338- Crankshaft Position Sensor “A” Circuit High

P0339- Crankshaft Position Sensor “A” Circuit Intermittent

The diagnostics for these 5 P Codes are the same. The circuit malfunction P Code means that a general error has been detected. The range/performance P Code means that an erratic error has been reported. The low input P Code means that too low of a voltage is being reported and the high input P Code means that too high of a voltage is being reported. The circuit intermittent P Code means that there has been a problem detected but only occasionally

These 5 P Codes all indicate the same thing: a failure with the Crankshaft Position Sensor and/or circuit. The only difference between the codes is the nature of the error being reported. The ECM constantly monitors the speed of your engine as it runs. It does this with a crankshaft position sensor. This sensor is necessary for your engine to start and continue to run after it’s been started. It tells the ECM exactly where each of the cylinders are in the 4 step combustion process. If you have one of these P Codes, the easiest thing to start with is to replace the Crankshaft Position Sensor. It’s not extremely expensive. It’s not necessarily cheap either but when compared with the price of diagnostics and labor to replace the sensor, it’s cost effective to start by replacing this sensor yourself. It’s a fairly easy repair. When you locate the Crankshaft Position Sensor, make sure you check inside the connector for any damage or corrosion. Check the wiring to the sensor in the immediate vicinity of the sensor for any kind of visible damage. If these things are ok, then replace the sensor and drive the vehicle to see if the problem still persists. If the condition is still present after this, you will want to visit your local repair shop at this point. The remaining causes of this P Code are wiring from the sensor to the ECM and the ECM itself. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The vehicle may not start at all or it may take an extended amount of time to start
  • Engine misfire
  • Engine stalls and will not restart
  • Engine hesitation/lack of power
  • In some extremely rare cases, there may be no observable symptoms

Possible causes:

  • Crankshaft Position Sensor
  • Wiring from the sensor to the ECM
  • ECM

Where to buy the parts:

The Crankshaft Position Sensor is readily available from your local aftermarket parts dealer. The quality of these parts is pretty reliable. As always, I strongly recommend you purchase the ECM from the manufacturer


P0340- Camshaft Position Sensor Circuit Malfunction

P0341- Camshaft Position Sensor Circuit Range/Performance

P0342- Camshaft Position Sensor Circuit Low

P0343- Camshaft Position Sensor Circuit High

P0344- Camshaft Position Sensor Circuit Intermittent

The diagnostics for these 5 P Codes are the same. The circuit malfunction P Code means that a general error has been detected. The range/performance P Code means that an erratic error has been reported. The low input P Code means that too low of a voltage is being reported and the high input P Code means that too high of a voltage is being reported. The circuit intermittent P Code means that there has been a problem detected but only occasionally

These 5 P Codes all indicate the same thing: a failure with the Camshaft Position Sensor and/or circuit. The Camshaft Position Sensor reports the position of the camshaft, or camshafts as a lot of modern vehicles have more than one, to the ECM. The ECM uses camshaft position to calculate the ignition spark timing and fuel injector timing. This tells the fuel injector exactly when to spray the fuel and the spark plug exactly when to ignite the fuel/air mixture in the combustion chamber, to get the most power it can for your engine. This timing of spark and fuel also helps to make the combustion process cleaner so your vehicle will have less harmful emissions coming out of the exhaust. If you have one of these DTC’s, the easiest thing to start with is to replace the Camshaft Position Sensor. It’s not extremely expensive. It’s not necessarily cheap either but when compared with the price of diagnostics and labor to replace the sensor, it’s cost effective to start by replacing this sensor yourself. It’s a fairly easy repair. When you locate the Camshaft Position Sensor, make sure you check inside the connector for any damage or corrosion. Check the wiring to the sensor in the immediate vicinity of the sensor for any kind of visible damage. If these things are ok, then replace the sensor and drive the vehicle to see if the problem still persists. If the condition is still present after this, you will want to visit your local repair shop at this point. The remaining causes of this P Code are wiring from the sensor to the ECM and the ECM itself. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The vehicle may not start at all or it may take an extended amount of time to start
  • Engine misfire
  • Engine stalls and will not restart
  • Engine hesitation/lack of power
  • In some extremely rare cases, there may be no observable symptoms

Possible causes:

  • Camshaft Position Sensor
  • Wiring from the sensor to the ECM
  • ECM

Where to buy the parts:

The Camshaft Position Sensor is readily available from your local aftermarket parts dealer. The quality of these parts is pretty reliable. As always, I strongly recommend you purchase the ECM from the manufacturer! ! The diagnostics for these 8 DTC’s are the same. The only difference is which cylinder is reporting the ignition coil error.


P0351- Ignition Coil “A” Circuit Primary/Secondary Malfunction

P0352- Ignition Coil “B” Circuit Primary/Secondary Malfunction

P0353- Ignition Coil “C” Circuit Primary/Secondary Malfunction

P0354- Ignition Coil “D” Circuit Primary/Secondary Malfunction

P0355- Ignition Coil “E” Circuit Primary/Secondary Malfunction

P0356- Ignition Coil “F” Circuit Primary/Secondary Malfunction

P0357- Ignition Coil “G” Circuit Primary/Secondary Malfunction

P0358- Ignition Coil “H” Circuit Primary/Secondary Malfunction

The diagnostics for these 8 P Codes are the same. The only difference between these P Codes is which ignition coil is reporting the error.

These P Codes only apply to vehicles that have the coil-on-plug spark system. This means that each cylinder has it’s own ignition coil pack, that sits directly on top of the spark plug. Each letter corresponds to a cylinder number. So ignition coil “A” means cylinder 1, and so on from there. The most likely cause of this P Code is the ignition coil or spark plug that’s reporting the failure. The easiest way to determine if you have a bad coil or spark plug causing this P Code, is to take the one that’s reporting the failure, and move it to a new cylinder. When you switch the coil to the new cylinder, make sure to change the spark plug to the new cylinder as well. Run the engine and drive it if the code doesn’t come back immediately. When the failure does show up, see if the code has switched to the new cylinder. For example: you have P Code P0351, so your cylinder 1 coil is reporting the error. Move the cylinder 1 coil and spark plug to cylinder 2, then drive the vehicle. When the check engine light comes back on, if the P Code is now P0352, then the coil or spark plug is the problem and needs to be replaced. When you replace one spark plug, you should always replace them all. Start with the spark plugs and then drive to see if the condition remains. If the problem still exists, then replace the coil for that cylinder and test again. If the P Code remains as P0351, then there is a problem with the circuit from the coil to the ECM. At this point you will need to visit your local repair shop. The diagnostics will require special tools to diagnose and/or repair. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Engine misfire/running rough. This may happen intermittently depending on if the coil is failing constantly or on occasion
  • Lack of power on acceleration
  • Possible black smoke coming from the exhaust (this means the engine is running rich)
  • It’s possible there won’t be any observable symptoms, but for this P Code, it’s highly unlikely

Possible causes:

  • Spark plug for the cylinder reporting the failure
  • Ignition coil for the cylinder reporting the failure
  • Wiring from the ignition coil to the ECM
  • ECM

Where to buy the parts:

The spark plugs are readily available from any aftermarket parts dealer. Don’t be fooled into buying the spark plugs that have 2 or more electrodes, and don’t buy the absolute cheapest spark plugs available for your engine. Either of these 2 possibilities will cause more problems than they fix. Buy the spark plugs that are recommended for your specific engine. Other than that, the reliability for these parts from the aftermarket dealers is perfectly reliable. The ignition coils for most vehicles are available from any local aftermarket parts dealer. The quality of these parts is fairly reliable. If you don’t want to take the chance on the parts, then I recommend buying from the manufacturer, providing you’re positive the coil is the problem. Once the coil has been installed, there is no returning the part. Electrical parts are not returnable for a refund. As always, I strongly recommend you purchase the ECM from the manufacturer






P0400- Exhaust Gas Recirculation Flow Malfunction

P0401- Exhaust Gas Recirculation Flow Insufficient Detected

P0402- Exhaust Gas Recirculation Flow Excessive Detected

The diagnostics for these 3 P Codes is the same. The only difference between the P codes is the type of error being reported. The flow malfunction P Code means that a general error has been reported with the flow of the Exhaust Gas Recirculation valve, or EGR valve. The flow insufficient P Code means that lower than expected flow has been reported. The high flow P Code means that higher than expected flow has been reported.

These 3 P Codes are essentially the same thing. They all describe a flow error for the EGR valve. The EGR valve is used to put some of the exhaust gasses back through the combustion process. This has the benefit of reducing combustion chamber temperatures, and reducing the dangerous emissions of your vehicle. If you have one of these P Codes the easiest and cheapest thing to do first, would be to replace the EGR valve assembly. WARNING: DO NOT TOUCH ANY EXHAUST COMPONENTS WHEN THE ENGINE IS HOT!! THE HOOD MUST BE OPEN WITH THE ENGINE OFF FOR A MINIMUM OF 2 HOURS BEFORE ANY EXHAUST SYSTEM REPAIRS ARE ATTEMPTED. There is no easy way to test EGR system for yourself at home. If you’ve replaced the EGR valve and this condition still exists, it’s time to visit your local repair shop. The remaining causes for these P Codes are going to be very difficult to diagnose, and will require several special tools that are quite costly. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There may be a surging at a light engine load, cruising at 45 miles per hour or more
  • Possible slight decrease in fuel mileage but most likely this won’t be enough to notice
  • It’s very probable that there won’t be any observable symptoms

Possible causes:

  • The EGR valve
  • A restriction to the EGR valve passages. This will be a carbon build up in the tubes coming off of the EGR valve. These tubes will need to be cleaned if there is a heavy carbon build up. In some cases, the intake manifold will need to be removed to do this
  • Lack of vacuum to the EGR solenoid, if the system for your vehicle has a vacuum operated solenoid
  • Differential EGR Pressure Feedback Sensor
  • ECM. I list this as a possibility for these P Codes because, technically, any of the P Codes the ECM reports can be caused by a defective ECM. It is extremely unlikely that the ECM is the cause of these P Codes

Where to buy the parts:

When replacing the EGR valve, I strongly recommend buying it from the manufacturer. The reliability of these parts from the aftermarket is highly unreliable. In the very unlikely even that the ECM ends up being the cause of this DTC, as always, I strongly recommend you purchase the ECM from the manufacturer


P0403- Exhaust Gas Recirculation Circuit Malfunction

P0404- Exhaust Gas Recirculation Circuit Range/Performance

P0405- Exhaust Gas Recirculation Circuit Low

P0406- Exhaust Gas Recirculation Circuit High

The diagnostics for these 4 P Codes are the same. The only difference is the nature of the error being reported. The circuit malfunction P Code means that a general error has been reported. The circuit range/performance P Code means that an erratic error has been reported. The circuit low P Code means that a lower than expected voltage has been reported. The circuit high P Code means that a higher than expected voltage has been reported.

These 4 P Codes are essentially the same thing. They all refer to the circuit that operates the EGR valve. The EGR valve is used to put some of the exhaust gasses back through the combustion process. This has the benefit of reducing combustion chamber temperatures, and reducing the dangerous emissions of your vehicle. If you have one of these DTC’s the easiest and cheapest thing to do first, would be to replace the EGR valve assembly. WARNING: DO NOT TOUCH ANY EXHAUST COMPONENTS WHEN THE ENGINE IS HOT!! THE HOOD MUST BE OPEN WITH THE ENGINE OFF FOR A MINIMUM OF 2 HOURS BEFORE ANY EXHAUST SYSTEM REPAIRS ARE ATTEMPTED. When replacing the EGR valve, make sure to check the connector when you unplug it. Check for any type of damage or corrosion inside the connector and check the wiring in the immediate are near the EGR valve. Even though these P Codes refer to the circuit of the EGR valve, the most likely cause is still the EGR valve itself. If the EGR sensor, which is a non-serviceable part of the EGR valve, has an internal electrical issue, it can cause any of these P Codes. There is no easy way to test EGR system for yourself at home. If you’ve replaced the EGR valve and this condition still exists, it’s time to visit your local repair shop. The remaining causes for these P Codes are going to be very difficult to diagnose, and will require several special tools that are quite costly. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There may be a surging at a light engine load, cruising at 45 miles per hour or more
  • Possible slight decrease in fuel mileage but most likely this won’t be enough to notice
  • It’s very probable that there won’t be any observable symptoms

Possible causes:

  • The EGR valve
  • A restriction to the EGR valve passages. This will be a carbon build up in the tubes coming off of the EGR valve. These tubes will need to be cleaned if there is a heavy carbon build up. In some cases, the intake manifold will need to be removed to do this
  • Lack of vacuum to the EGR solenoid, if the system for your vehicle has a vacuum operated solenoid
  • Differential EGR Pressure Feedback Sensor
  • The wiring from the EGR valve to the ECM
  • ECM

Where to buy the parts:

When replacing the EGR valve, I strongly recommend buying it from the manufacturer. The reliability of these parts from the aftermarket is highly unreliable. As always, I strongly recommend you purchase the ECM from the manufacturer!


P0420- Catalyst System Efficiency Below Threshold Bank 1

P0421- Warm Up Catalyst System Efficiency Below Threshold Bank 1

P0422- Main Catalyst System Efficiency Below Threshold Bank 1

The diagnostics for these 3 P Codes are the same. The only difference between these P Codes is the nature of the failure being reported

These 3 P Codes are essentially the same thing. They all report a failure of the catalytic converter system, just a different kind of failure for the different P Codes. These P Codes are for a failure in the converters efficiency on bank 1. Bank 1 is the side of the engine where cylinder 1 is located. The catalytic converter is an essential part of your exhaust system. It’s function is to oxidize the harmful emissions that come out of your engine and turn them into harmless atmospheric gasses. The converter accomplishes this with the use of precious metals, such as platinum. When you find out the price of a catalytic converter, you may be tempted to wonder if it’s made out of gold. Instead it’s platinum! The catalytic converter is not something that can be easily replaced at your home, by yourself. If you have one of these P Codes make sure your engine is running correctly. If there is a misfire present, this will absolutely cause one of these P Codes. If the engine is running correctly, and there are no other P Codes present, then it’s time to visit your local repair shop. Replacing your catalytic converter at home is just not practical. If there are other P Codes present, diagnose and repair those first. After those repairs have been made, test drive extensively to see if any of these P Codes return. I say to test drive extensively because it normally takes quite a while to set these P Codes. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Lack of power/acceleration. This will happen if your catalytic converter has come apart inside and has clogged the flow of the exhaust
  • Providing the engine is running correctly, there will be no noticeable symptoms

Possible causes:

  • Engine misfire
  • Internal engine failure, causing a rise in dangerous emission gasses
  • Catalytic converter for Bank 1
  • ECM. This is extremely unlikely for these P Codes

Where to buy the parts:

If the local muffler/exhaust shop near you is reputable, then I recommend taking it there to be the most cost effective. The aftermarket catalytic converters, usually don’t fit exactly right. They have to be welded in to place to be absolutely correct most of the time. They can be clamped into place effectively, providing the person that’s doing it, knows what they’re doing. If there isn’t a good local muffler shop, then I definitely recommend taking it to the manufacture. The parts and labor will be more expensive but the piece of mind is worth the price under these circumstances. IMPORTANT NOTE: The catalytic converter is covered by an extended federal emissions warranty of 8 years or 80,000 miles. Every vehicle on the road has this warranty coverage for the converters it is originally equipped with. As always, I strongly recommend you purchase the ECM from the manufacturer! !!


P0430- Catalyst System Efficiency Below Threshold Bank 2

P0431- Warm Up Catalyst System Efficiency Below Threshold Bank 2

P0432- Main Catalyst System Efficiency Below Threshold Bank 2

The diagnostics for these 3 P Codes are the same. The only difference between these codes is the nature of the failure being reported

These 3 P Codes are essentially the same thing. They all report a failure of the catalytic converter system, just a different kind of failure for the different P Codes. These P Codes are for a failure in the converters efficiency on bank 2. Bank 2 is the side of the engine where cylinder 2 is located. The catalytic converter is an essential part of your exhaust system. It’s function is to oxidize the harmful emissions that come out of your engine and turn them into harmless atmospheric gasses. The converter accomplishes this with the use of precious metals, such as platinum. When you find out the price of a catalytic converter, you may be tempted to wonder if it’s made out of gold. Instead it’s platinum! The catalytic converter is not something that can be easily replaced at your home, by yourself. If you have one of these P Codes make sure your engine is running correctly. If there is a misfire present, this will absolutely cause one of these P Codes. If the engine is running correctly, and there are no other P Codes present, then it’s time to visit your local repair shop. Replacing your catalytic converter at home is just not practical. If there are other P Codes present, diagnose and repair those first. After those repairs have been made, test drive extensively to see if any of these P Codes return. I say to test drive extensively because it normally takes quite a while to set these P Codes. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Lack of power/acceleration. This will happen if your catalytic converter has come apart inside and has clogged the flow of the exhaust
  • Providing the engine is running correctly, there will be no noticeable symptoms

Possible causes:

  • Engine misfire
  • Internal engine failure, causing a rise in dangerous emission gasses
  • Catalytic converter for Bank 1
  • ECM. This is extremely unlikely for these P Codes

Where to buy the parts:

If the local muffler/exhaust shop near you is reputable, then I recommend taking it there to be the most cost effective. The aftermarket catalytic converters, usually don’t fit exactly right. They have to be welded in to place to be absolutely correct most of the time. They can be clamped into place effectively, providing the person that’s doing it, knows what they’re doing. If there isn’t a good local muffler shop, then I definitely recommend taking it to the manufacture. The parts and labor will be more expensive but the piece of mind is worth the price under these circumstances. IMPORTANT NOTE: The catalytic converter is covered by an extended federal emissions warranty of 8 years or 80,000 miles. Every vehicle on the road has this warranty coverage for the converters it is originally equipped with. As always, I strongly recommend you purchase the ECM from the manufacturer


P0440- Evaporative Emissions Control System Malfunction

This P Code means that the Evaporative Emissions System has detected some type of malfunction. This system was created to store fuel vapors that have escaped from the fuel system. This is not to be confused with liquid fuel. If you have one of the Evaporative Emissions System P Codes, it does not indicate that you have a liquid fuel leak. This is to tell you that your vehicle is releasing harmful gasses into the atmosphere. There are several components for this system. Including, but not limited to: the fuel cap, the fuel tank, the fuel pump seal, the vent valve on top of the fuel tank, the fuel vapor lines from the tank forward, the liquid fuel lines, the fuel vapor canister, the purge valve, and the vacuum lines. This system is completely closed to the atmosphere when it’s operating correctly and is equipped with a very simple method to test the integrity of the entire system. A vacuum is drawn on the system, and then it’s monitored to see if it maintains the vacuum. If it loses the vacuum, or can’t ever attain the vacuum, then this is one of several P Codes that can be set. If you have this P Code by itself and no other Evaporative Emissions P Code, then the problem could be in any part of the system. There are several places you can look first before needing to visit a repair shop. First things first, check the gas cap. Especially if you’ve put gas in your vehicle recently, the fuel cap being left loose, or off entirely, is the number one cause for a problem with the Evaporative Emissions System. There is a seal in the fuel cap but it can’t be tested without specialized equipment. If you suspect that your fuel cap seal is leaking, then I recommend replacing it to see if the issue is resolved. If the fuel cap is tight, then look under the vehicle and make sure you don’t see any signs of a liquid fuel leak. WARNING: A LIQUID FUEL LEAK IS EXTREMELY DANGEROUS! I CANNOT STRESS THIS ENOUGH, IF YOU SUSPECT A LIQUID FUEL LEAK, HAVE THE VEHICLE TOWED TO YOUR LOCAL REPAIR SHOP AND HAVE IT REPAIRED BEFORE DRIVING THE VEHICLE AGAIN. If there are no signs of a liquid fuel leak, then locate the fuel vapor canister, and the lines coming from the fuel tank to the canister. Visually inspect the canister and the lines. Make sure there is no physical damage to the canister and no cracks or splits in the rubber lines. If you find any issues with any of these things, repair them and drive the vehicle. It could take several days for this P Code to reset depending on your driving habits. After you’ve checked these few things, you’re next best step will be to visit your local repair shop. The remaining causes for this P Code cannot be easily tested at your house. The most effective way to test the system is with a scanner and a machine that emits smoke that has a special dye in it that shows up with a black light. As you can imagine, this testing equipment is very expensive. There is some good news though, if it has been determined that there is no liquid fuel leak, you can drive your vehicle for as long as you like, without any adverse effects. Your check engine light will stay on but that’s the only thing that will happen. There can be a very minor drop in your fuel mileage but most likely, it’ll be so slight that you wont even notice it. I strongly recommend that you have the diagnosis performed to make sure that there is not a liquid fuel leak. Once you’ve been advised that there is no liquid fuel leak, you can just keep driving without having to repair this P Code. I recommend having the diagnosis confirmed by a professional technician for safety reasons. If a liquid fuel leak goes un-repaired, it can easily result in a vehicle fire. If you choose not to repair the cause of this P Code, make sure that you continue to check the codes stored in your ECM, to be sure that no other P Codes have showed up. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be no observable symptoms for this P Code

Possible causes:

  • Loose fuel cap or fuel cap left completely off. Suspect this as the cause first if you’ve recently put fuel in your vehicle
  • The fuel cap does have a seal in it that can leak. You can’t test it without special equipment
  • A split or cracked rubber line for the fuel vapors
  • Damaged fuel vapor canister
  • Fuel pump seal
  • Purge valve internal leak or malfunction
  • Vacuum lines from the purge valve to the intake manifold
  • In some extremely rare cases, the ECM can be the cause

Where to buy the parts:

For the most common cause, the fuel cap, I recommend buying the cap from the manufacturer. The fuel cap is readily available from the manufacturer or the aftermarket parts dealer, however, the reliability of these parts from the aftermarket dealer is pretty unreliable. The rest of the parts that can cause this are usually not available from the aftermarket parts dealers for most vehicles. If the cause of this DTC is just a split rubber hose, you can get fuel vapor hose from almost anywhere. As always, I strongly recommend you purchase the ECM from the manufacturer


P0441- Evaporative Emission System Malfunction Incorrect Purge Flow

This P Code means the Evaporative Emissions System has detected a malfunction with the purge flow specifically. Which means that when the ECM is monitoring the purge valve, it’s not seeing the purge valve respond the way it should. This could mean the valve is staying on too long, not long enough, or not coming on at all. The Evaporative Emissions System was created to store fuel vapors that have escaped from the fuel system. This is not to be confused with liquid fuel. If you have one of the Evaporative Emissions System P Codes, it does not indicate that you have a liquid fuel leak. This is to tell you that your vehicle is releasing harmful gasses into the atmosphere. There are several components for this system. Including, but not limited to: the fuel cap, the fuel tank, the fuel pump seal, the vent valve on top of the fuel tank, the fuel vapor lines from the tank forward, the liquid fuel lines, the fuel vapor canister, the purge valve, and the vacuum lines. This system is completely closed to the atmosphere when it’s operating correctly and is equipped with a very simple method to test the integrity of the entire system. A vacuum is drawn on the system, and then it’s monitored to see if it maintains the vacuum. If it loses the vacuum, or can’t ever attain the vacuum, then this is one of several P Codes that can be set. If you have this P Code by itself and no other Evaporative Emissions P Codes, then the problem could be in any part of the system. There are several places you can look first before needing to visit a repair shop. First things first, check the gas cap. Especially if you’ve put gas in your vehicle recently, the fuel cap being left loose, or off entirely, is the number one cause for a problem with the Evaporative Emissions System. There is a seal in the fuel cap but it can’t be tested without specialized equipment. If you suspect that your fuel cap seal is leaking, then I recommend replacing it to see if the issue is resolved. If no problems are found or suspected with the fuel cap, then I would recommend replacing the purge valve before going to your local repair shop. The purge valve isn’t drastically expensive and will cost less than the normal diagnostic fee. Once this is done, drive the vehicle for a few days and see if the code returns. After you’ve checked these few things, you’re next best step will be to visit your local repair shop. The remaining causes for this P Code cannot be easily tested at your house. The most effective way to test the system is with a scanner and a machine that emits smoke that has a special dye in it that shows up with a black light. As you can imagine, this testing equipment is very expensive. There is some good news though, if it has been determined that there is no liquid fuel leak, you can drive your vehicle for as long as you like, without any adverse effects. Your check engine light will stay on but that’s the only thing that will happen. There can be a very minor drop in your fuel mileage but most likely, it’ll be so slight that you wont even notice it. I strongly recommend that you have the diagnosis performed to make sure that there is not a liquid fuel leak. Once you’ve been advised that there is no liquid fuel leak, you can just keep driving without having to repair this code. I recommend having the diagnosis confirmed by a professional technician for safety reasons. If a liquid fuel leak goes un-repaired, it can easily result in a vehicle fire. If you choose not to repair the cause of this P Code, make sure that you continue to check the P Codes stored in your ECM, to be sure that no other P Codes have showed up. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be no observable symptoms for this P Code

Possible causes:

  • Loose fuel cap or fuel cap left completely off. Suspect this as the cause first if you’ve recently put fuel in your vehicle
  • The fuel cap does have a seal in it that can leak. You can’t test it without special equipment
  • The purge valve
  • A split or cracked rubber line for the fuel vapors
  • Damaged fuel vapor canister
  • Fuel pump seal
  • Vacuum lines from the purge valve to the intake manifold
  • In some extremely rare cases, the ECM can be the cause

Where to buy the parts:

For the most common cause, the fuel cap, I recommend buying the cap from the manufacturer. The fuel cap is readily available from the manufacturer or the aftermarket parts dealer, however, the reliability of these parts from the aftermarket dealer is pretty unreliable. The rest of the parts that can cause this are usually not available from the aftermarket parts dealers for most vehicles. If the cause of this P Code is just a split rubber hose, you can get fuel vapor hose from almost anywhere. As always, I strongly recommend you purchase the ECM from the manufacturer


P0442- Evaporative Emissions System Leak Detected (small leak)

P0455- Evaporative Emissions System Leak Detected (large leak)

P0456- Evaporative Emissions System Leak Detected (medium or small leak)

The diagnostics for these 3 P Codes is exactly the same. The only difference in these P Codes is the size of the leak that’s being reported

This P Code  means that the Evaporative Emissions System has detected a leak in the system. A leak in this system is reported in one of two ways. The system can’t be brought to the full level of vacuum that the ECM wants to see, or once the full vacuum has been achieved, the system loses the vacuum pressure. This system was created to store fuel vapors that have escaped from the fuel system. This is not to be confused with liquid fuel. If you have one of the Evaporative Emissions System P Codes, it does not indicate that you have a liquid fuel leak. This is to tell you that your vehicle is releasing harmful gasses into the atmosphere. There are several components for this system. Including, but not limited to: the fuel cap, the fuel tank, the fuel pump seal, the vent valve on top of the fuel tank, the fuel vapor lines from the tank forward, the liquid fuel lines, the fuel vapor canister, the purge valve, and the vacuum lines. This system is completely closed to the atmosphere when it’s operating correctly and is equipped with a very simple method to test the integrity of the entire system. A vacuum is drawn on the system, and then it’s monitored to see if it maintains the vacuum. If it loses the vacuum, or can’t ever attain the vacuum, then this is one of several P Codes that can be set. If you have this P Code by itself and no other Evaporative Emissions P Codes, then the problem could be in any part of the system. There are several places you can look first before needing to visit a repair shop. First things first, check the gas cap. Especially if you’ve put gas in your vehicle recently, the fuel cap being left loose, or off entirely, is the number one cause for a problem with the Evaporative Emissions System. There is a seal in the fuel cap but it can’t be tested without specialized equipment. If you suspect that your fuel cap seal is leaking, then I recommend replacing it to see if the issue is resolved. If the fuel cap is tight, then look under the vehicle and make sure you don’t see any signs of a liquid fuel leak. WARNING: A LIQUID FUEL LEAK IS EXTREMELY DANGEROUS! I CANNOT STRESS THIS ENOUGH, IF YOU SUSPECT A LIQUID FUEL LEAK, HAVE THE VEHICLE TOWED TO YOUR LOCAL REPAIR SHOP AND HAVE IT REPAIRED BEFORE DRIVING THE VEHICLE AGAIN. If there are no signs of a liquid fuel leak, then locate the fuel vapor canister, and the lines coming from the fuel tank to the canister. Visually inspect the canister and the lines. Make sure there is no physical damage to the canister and no cracks or splits in the rubber lines. If you find any issues with any of these things, repair them and drive the vehicle. It could take several days for this P Code to reset depending on your driving habits. After you’ve checked these few things, you’re next best step will be to visit your local repair shop. The remaining causes for this P Code cannot be easily tested at your house. The most effective way to test the system is with a scanner and a machine that emits smoke that has a special dye in it that shows up with a black light. As you can imagine, this testing equipment is very expensive. There is some good news though, if it has been determined that there is no liquid fuel leak, you can drive your vehicle for as long as you like, without any adverse effects. Your check engine light will stay on but that’s the only thing that will happen. There can be a very minor drop in your fuel mileage but most likely, it’ll be so slight that you wont even notice it. I strongly recommend that you have the diagnosis performed to make sure that there is not a liquid fuel leak. Once you’ve been advised that there is no liquid fuel leak, you can just keep driving without having to repair this code. I recommend having the diagnosis confirmed by a professional technician for safety reasons. If a liquid fuel leak goes un-repaired, it can easily result in a vehicle fire. If you choose not to repair the cause of this P Code, make sure that you continue to check the P Codes stored in your ECM, to be sure that no other P Codes have showed up. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be no observable symptoms for this P Code

Possible causes:

  • Loose fuel cap or fuel cap left completely off. Suspect this as the cause first if you’ve recently put fuel in your vehicle
  • The fuel cap does have a seal in it that can leak. You can’t test it without special equipment
  • A split or cracked rubber line for the fuel vapors
  • Damaged fuel vapor canister
  • Fuel pump seal
  • Purge valve internal leak or malfunction
  • Vacuum lines from the purge valve to the intake manifold
  • In some extremely rare cases, the ECM can be the cause

Where to buy the parts:

For the most common cause, the fuel cap, I recommend buying the cap from the manufacturer. The fuel cap is readily available from the manufacturer or the aftermarket parts dealer, however, the reliability of these parts from the aftermarket dealer is pretty unreliable. The rest of the parts that can cause this are usually not available from the aftermarket parts dealers for most vehicles. If the cause of this P Code is just a split rubber hose, you can get fuel vapor hose from almost anywhere. As always, I strongly recommend you purchase the ECM from the manufacturer


P0443- Evaporative Emissions System Purge Valve Control Circuit

P0444- Evaporative Emissions System Purge Valve Control Circuit Open

P0445- Evaporative Emissions System Purge Valve Control Circuit Shorted

The diagnostics for these 3 P Codes is the same. The only difference between these P Codes is the nature of the error being reported. The control valve circuit P Code means there’s been a problem with the purge valve circuit reported. The control valve circuit open P Code means that high resistance or an open circuit has been reported. The control valve circuit shorted P Code means that there is too much voltage on the circuit or there is voltage on the circuit when there shouldn’t be

These 3 P Codes are essentially the same thing. They are all indicating a problem with the Purge Valve Control Circuit, meaning these codes are an electrical failure. The Purge Valve is a part of the Evaporative Emissions System. This system was created to store fuel vapors that have escaped from the fuel system. This is not to be confused with liquid fuel. If you have one of the Evaporative Emissions System P Codes, it does not indicate that you have a liquid fuel leak. This is to tell you that your vehicle is releasing harmful gasses into the atmosphere. There are several components for this system. Including, but not limited to: the fuel cap, the fuel tank, the fuel pump seal, the vent valve on top of the fuel tank, the fuel vapor lines from the tank forward, the liquid fuel lines, the fuel vapor canister, the purge valve, and the vacuum lines. This system is completely closed to the atmosphere when it’s operating correctly and is equipped with a very simple method to test the integrity of the entire system. A vacuum is drawn on the system, and then it’s monitored to see if it maintains the vacuum. When the system is operating as it’s designed, the Purge Valve is how these fuel vapors get sent to the combustion chamber to be burned like normal fuel. If you have one of these P Codes the most likely cause is the Purge Valve itself, or the Purge Valve solenoid. Most vehicles have the Purge Valve and the solenoid as a single unit, but in some rare cases they are separate. If your vehicle is one of the ones that has a separate valve and solenoid, then these P Codes apply to the solenoid part of the system. Make sure to check the connector of the Purge Valve, or solenoid, for any damage or corrosion. If none is found, then check the wiring for the valve or solenoid in the immediate area. After the initial inspection of the connector and immediate wiring has been made, the most cost effective place to start is by replacing the Purge Valve assembly, or the solenoid, and drive the vehicle to see if the problem still exists. It may take several days for this P Code to reset (if there is still a problem with the system) depending on your driving habits. At this point if the problem still exists, it’s time to visit your local repair shop. The remaining causes will require a diagnosis of the electrical circuit for this system and are not easily done at your house. It’ll require specialized tools to complete. There is some good news though, for these 3 P Codes, you can drive your vehicle for as long as you like, without any adverse effects. Your check engine light will stay on but that’s the only thing that will happen. There can be a very minor drop in your fuel mileage but most likely, it’ll be so slight that you wont even notice it. If you choose not to repair the cause of this P Code, make sure that you continue to check the P Codes stored in your ECM, to be sure that no other P Codes have showed up. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be no observable symptoms for this P Code

Possible causes:

  • The Purge Valve assembly or the solenoid if the 2 parts are separate for your vehicle
  • Wiring issue from the valve to the ECM
  • ECM

Where to buy the parts:

The purge valve for some vehicles is not available from the aftermarket parts dealers. If it is available for your vehicle, the quality of these parts is mostly reliable. As always, I strongly recommend you purchase the ECM from the manufacturer


P0446- Evaporative Emission System Vent Valve Control Circuit Malfunction

P0447- Evaporative Emission System Vent Valve Control Circuit Open

P0448- Evaporative Emission System Vent Valve Control Circuit Shorted

The diagnostics for these 3 P Codes is the same. The only difference between these P Codes is the nature of the error being reported. The valve control circuit malfunction P Code means there’s been a problem with the purge valve circuit reported. The valve control circuit open P Code means that high resistance or an open circuit has been reported. The valve control circuit shorted P Code means that there is too much voltage on the circuit or there is voltage on the circuit when there shouldn’t be

These 3 P Codes are essentially the same thing. They are all indicating a problem with the Vent Valve Control Circuit, meaning these codes are an electrical failure. The Vent Valve is a part of the Evaporative Emissions System. This system was created to store fuel vapors that have escaped from the fuel system. This is not to be confused with liquid fuel. If you have one of the Evaporative Emissions System P Codes, it does not indicate that you have a liquid fuel leak. This is to tell you that your vehicle is releasing harmful gasses into the atmosphere. There are several components for this system. Including, but not limited to: the fuel cap, the fuel tank, the fuel pump seal, the vent valve on top of the fuel tank, the fuel vapor lines from the tank forward, the liquid fuel lines, the fuel vapor canister, the purge valve, and the vacuum lines. This system is completely closed to the atmosphere when it’s operating correctly and is equipped with a very simple method to test the integrity of the entire system. A vacuum is drawn on the system, and then it’s monitored to see if it maintains the vacuum.The Vent Valve Control Circuit closes off the vent valve to make sure a vacuum can be drawn on the evaporative emissions system. If the circuit fails, then the valve doesn’t close, and you will get one of these P Codes plus one or more P Codes pertaining to an evap system leak. The Vent Valve is the most likely cause of this P Code. Make sure to check the connector of the Vent Valve for any damage or corrosion. If none is found, then check the wiring for the Vent Valve in the immediate area. If no issues are found there, then I recommend a visit to your local repair shop at this point. The vent valve for almost all modern vehicles is a part of the fuel tank that can’t be replaced separately from the fuel tank. If your vehicle is one of the few that has a separate Vent Valve, I recommend replacing it before the repair shop visit. There is some good news though, for these 3 P Codes, you can drive your vehicle for as long as you like, without any adverse effects. Your check engine light will stay on but that’s the only thing that will happen. There can be a very minor drop in your fuel mileage but most likely, it’ll be so slight that you wont even notice it. If you choose not to repair the cause of this P Code, make sure that you continue to check the P Codes stored in your ECM, to be sure that no other P Codes have showed up. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There will be no observable symptoms for this P Code

Possible causes:

  • The Vent Valve itself. For most of you this will mean the fuel tank must be replaced if this is the cause
  • Wiring issue from the valve to the ECM
  • ECM

Where to buy the parts:

If the fuel tank for your vehicle is available from your local aftermarket parts dealer, then I recommend buying it from there. The reliability for these parts is perfectly acceptable. If the Vent Valve is separate from the fuel tank for your vehicle, this part is also perfectly reliable from your aftermarket parts dealer. As always, I strongly recommend you purchase the ECM from the manufacturer


P0460- Fuel Level Sensor Circuit Malfunction

P0461- Fuel Level Sensor Circuit Range/Performance

P0462- Fuel Level Sensor Circuit Low

P0463- Fuel Level Sensor Circuit High

P0464- Fuel Level Sensor Circuit Intermittent

The diagnostics for these 5 P Codes are the same. The only difference between them is the nature of the error being reported. The circuit malfunction P Code means that a general error has been detected. The range/performance P Code means that an erratic error has been reported. The low input P Code means that too low of a voltage is being reported and the high input P Code means that too high of a voltage is being reported. The circuit intermittent P Code means that there has been a problem detected but only occasionally

These 5 P Codes are essentially the same thing. The only difference is the nature of the error being reported. They all indicate an electrical failure with the Fuel Level Sensor. This sensor does exactly what it sounds like, it tells you how much fuel is left in your tank. So you can see why this one is so important! If you have one of these P Codes I recommend a visit to your local repair shop. The Fuel Level Sensor, or Fuel Level Sending Unit as it’s called for some vehicles, is attached to your fuel pump and sits inside the fuel tank. The connector for the fuel pump on most vehicles is on top of the fuel tank and not easy to access. In some cases there is an access to the fuel pump under the rear seat of your car or in the trunk. If this is the case, then access the fuel pump and inspect the connector for any damage or corrosion. If none is found, check the wiring in the immediate vicinity for damage. If you don’t find any damage there, then I recommend a visit to your local repair shop at this point. The most likely cause of these P Codes is the Fuel Level Sensor, but most of the time it has to be purchased as part of the fuel pump module. This is a pretty expensive part to replace unless you’re sure that’s what the failed part is. If the Fuel Level Sensor is not the failed part, then the diagnosis for the remaining causes will require specialized tools. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The most common symptom will be that the fuel gauge is reading wrong. It may show that you have fuel left in the tank when you have none, or it may show that you have low to no fuel when you just filled the tank
  • If the gauge is reading incorrectly, this can be the cause of your vehicle not starting because it’s out of fuel

Possible causes:

  • Fuel Level Sensor
  • Wiring from the fuel pump to the ECM
  • ECM
  • In some vehicles the BCM, or Body Control Module, is responsible for reporting the fuel level to the fuel gauge

Where to buy the parts:

If your Fuel Level Sensor can be replaced separately from the fuel pump, then these parts are perfectly reliable from your aftermarket parts dealer. The fuel pump module is fairly reliable from the aftermarket parts dealer as well. If the BCM is the cause, then I strongly recommend that you purchase it form the manufacturer. In most vehicles that have a BCM it will have to be programmed with the correct software just as the ECM does. As always, I strongly recommend you purchase the ECM from the manufacturer


P0480- Cooling Fan #1 Control Circuit Malfunction

P0481- Cooling Fan #2 Control Circuit Malfunction

The diagnostics for these 2 P Codes is the same. The only difference is the Fan Control Circuit that’s reporting the error

These 2 P Codes are for the Electric Cooling Fan Circuits. The Cooling Fan is a very simple system. The ECM tells the Cooling Fan to turn on and then watches the electrical output of the fan, or fans if your vehicle is equipped with 2, to see if the fan(s) turned on and are cooling the engine as much as it expects. There is no easy way to describe how to determine which fan is #1 and which is #2. I recommend consulting a repair manual to help figure out which is which. These codes are both indicators of a general failure of the system and not necessarily a problem with just the Cooling Fan motor itself. If you have one of these P Codes make sure there are no coolant leaks before you start checking the electrical system of the Cooling Fans. Provided there are no leaks with the cooling system, check the Cooling Fan relay. The relays are usually in the PDC, or Power Distribution Center, which is normally under the hood somewhere. Some vehicles will have a list of the functions of the relays on the bottom of the PDC cover. Other vehicles will have this information in the owners manual. It’s not easy to see that the relay is bad just by looking at it but a replacement relay is very inexpensive, and can be purchased from your local aftermarket parts dealer. I recommend replacing the relay and while doing that, make sure there is no corrosion in the terminals of the PDC. If there is, that will need to be fixed and the relay replaced. The corrosion inside of a PDC is not very easy to clean because you won’t be able to see the bottom of the terminal or the wires to make sure they’re not damaged, and the PDC is not easy to disassemble and repair. If you find corrosion in the PDC, then I recommend going to your local repair shop to have this repair done, unless you’re pretty familiar with how to repair these types of electrical systems. NEVER REMOVE THE AIR BAG RELAY FOR ANY REASON. IF NOT DONE PROPERLY, YOU CAN EXPLODE YOUR AIRBAGS AND NOT ONLY IS THIS A VERY COSTLY MISTAKE, IT’S POTENTIALLY DEADLY!! I want to make sure to warn you of the danger of the airbag electrical system, it’s not something to take lightly. If you’ve found no corrosion, put a different relay in place then start the engine and let it heat up to operating temperature. The Cooling Fan will generally come on between 220 Degrees Fahrenheit to 235 Degrees Fahrenheit. If the fan doesn’t come on during this time then there is an electrical issue. The last thing to check before visiting your local repair shop, is the electrical connector for the cooling fan(s). Check this connector for any corrosion or obvious damage to the connector and wiring in the immediate area of the Cooling Fan. Also look at the Cooling Fan motor itself. If you see any corrosion on the Cooling Fan motor itself, then you’ll need to replace that. Once all of these things have been checked/repaired, it’s time to visit your local repair shop. The causes left will be electrical and will require specialized tools to diagnose. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The first symptom will likely be that your vehicle is overheating
  • The engine overheating can cause engine performance issues if it gets hot enough, such as, pinging or a misfire
  • In some extremely rare cases, there will be no observable symptoms

Possible causes:

  • Cooling Fan relay/Cooling Fan relay terminals in the PDC
  • Cooling Fan motor
  • Wiring issue between the Cooling Fan and the ECM
  • ECM

Where to buy the parts:

The Cooling Fan relay, and Cooling Fan motor, readily available from your aftermarket parts dealer. These parts are very reliable from the aftermarket parts store. As always, I strongly recommend you purchase the ECM from the manufacturer





P0500- Vehicle Speed Sensor Malfunction

P0501- Vehicle Speed Sensor Range/Performance

P0502- Vehicle Speed Sensor Low Input

P0503- Vehicle Speed Sensor Intermittent/High

The diagnostics for these 4 P Codes are the same. The only difference between them is the nature of the error being reported. The malfunction P Code means that a general error has been detected. The range/performance P Code means that an erratic error has been reported. The low input P Code means that too low of a voltage is being reported and the intermittent/high P Codes mean that too high of a voltage is being reported or the voltage is being reported only some of the time.

These P Codes all mean basically the same thing. The Vehicle Speed Sensor is not being read correctly by the ECM. These P Codes will only appear on vehicles that have a Vehicle Speed Sensor that reports to the ECM, which is usually mounted in the rear differential. If you have one of these P Codes make sure to consult a repair manual for the correct location of the Speed Sensor. The first thing to check is the connector for the Speed Sensor. Look for any corrosion inside the connector and check the wiring in the immediate vicinity of the Speed Sensor connector for damage. If no issues are found with these things, then the most cost effective thing to do at this point is to replace the Speed Sensor. You can get these sensors relatively cheap, and most of the time, they’re pretty easy to replace. Once the sensor has been replaced, drive the vehicle and see if the condition is still present. If the problem still exists, it’s time to visit your local repair shop because the remaining causes of these P Codes will be electrical and will require specialized tools to diagnose. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The speedometer won’t read any speed at all when the vehicle is moving
  • The transmission may not shift correctly or at all
  • In some rare cases, there may be no observable symptoms. This is pretty unlikely for these P Codes

Possible causes:

  • Vehicle Speed Sensor
  • Wiring from the Sensor to the ECM
  • Improper tire size programmed into the module. This can happen but isn’t extremely likely if the vehicle has higher mileage
  • ECM

Where to buy the parts:

The Vehicle Speed sensor for some vehicles is available from the aftermarket parts dealer. The reliability of these sensors is pretty high. As always, I strongly recommend you purchase the ECM from the manufacturer


P0505- Idle Control System Malfunction

P0506- Idle Control System RPM Lower Than Expected

P0507- Idle Control System RPM Higher Than Expected

The diagnostics for these 3 P Codes is the same. The only difference between these P Codes is the nature of the error being reported. The system malfunction P Code means that a general error is being reported. The RPM lower than expected P Code means the engine speed is lower than the ECM expects, and the RPM higher than expected P Code means the engine speed is higher than expected

These P Codes are all essentially the same thing. They all indicate a problem with the IAC, or Idle Air Control, valve. This valve is mounted to the throttle body and it is basically a computer controlled vacuum leak. No matter what, your engine has to have a constant air supply to keep running. The throttle plate, which is controlled by the gas pedal, is open when you’re driving so that takes care of the needs of the air for the engine. When you’re vehicle is sitting still with the engine running is when you need the IAC valve. This valve will open according to how much air is needed to keep the engine running. This valve is pretty unique because the valve can open in increments so the ECM can add or take away air flow as needed. If you get one of these P Codes, check the connector for the IAC valve for any type of corrosion or damage. If none is found, check the wiring in the immediate area of the valve. If there are no problems found with either of these then check the throttle plate itself. If there is a heavy buildup of carbon coating the throttle plate and the inside of the throttle body, clean it completely, along with the bore of the throttle body, and test drive the vehicle to see if the condition still exists. If the problem is still evident, then I recommend replacing the IAC valve. Once the valve has been replaced, test drive the vehicle to see if the condition still exists. If the condition is still present, it’s time for a visit to your local repair shop. The remaining causes will be electrical and will require specialized tools to diagnose. NOTE: there is a decent amount of vehicles that have a system called “Electronic Throttle Control” If your vehicle is one of these, I recommend visiting your local repair shop to begin the diagnosis. This system is completely electronic and the throttle body assembly contains the IAC valve. If it needs to be replaced, it’s pretty expensive, so you want to be sure that’s the repair that’s needed. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The engine has high idle. This will be noticed when you’re sitting still and the engine is racing or surging
  • The engine stalls when you let off the gas pedal suddenly or when the vehicle stops moving

Possible causes:

  • IAC valve
  • Wiring from the valve to the ECM
  • ECM. This is pretty unlikely for these codes but not impossible

Where to buy the parts:

For some vehicles, the IAC valve will not be available from the aftermarket parts dealers. If the IAC valve is available for your vehicle from the aftermarket, the quality of these parts is fairly reliable. If you have one of the vehicles with Electronic Throttle Control, the throttle body is only available for purchase from the manufacturer. As always, I strongly recommend you purchase the ECM from the manufacturer


P0526- Fan Speed Sensor Circuit

P0527- Fan Speed Sensor Range/Performance

P0528- Fan Speed Sensor No Signal

P0529- Fan Speed Sensor Intermittent

The diagnostics for these 4 P Codes is the same. The only difference between these P Codes is the nature of the error that’s being reported. The sensor circuit P Code means that a general error is being reported. The range/performance P Code means an erratic error has been reported. The no signal P Code means that the ECM is not seeing any return voltage from the sensor. The intermittent P Code means that the sensor is reading normally but only some of the time

These 4 P Codes are basically the same thing. They all indicate that the ECM is not reading the Cooling Fan Speed Sensor correctly. The Cooling Fan Speed Sensor is only used on some vehicles. It is used for exactly what you already think it’s for, to tell the ECM how fast the fan is moving. This code is very simple. Check the Fan Speed Sensor connector for any corrosion or damage. Next, check the wiring in the immediate vicinity of the connector for any signs of damage. If neither of these conditions is apparent, then I recommend replacing the Fan Speed Sensor. For some vehicles, this may mean the entire Cooling Fan assembly needs to be replaced, although this is the exception and not the rule. Once the sensor has been replaced, test drive the vehicle and see if the condition is still present. If the problem still exists, it’s time to visit your local repair shop. The remaining causes for these P Codes are electrical and will require specialized tools to diagnose. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • Vehicle is overheating
  • It’s somewhat likely that there will be no observable symptoms

Possible causes:

  • Fan Speed Sensor
  • Wiring from the sensor to the ECM
  • ECM

Where to buy the parts:

If the Fan Speed Sensor for your vehicle is able to be purchased separately from the the fan, then this part can be purchased from your local aftermarket parts dealer. The quality of this sensor is fairly reliable from the aftermarket dealer. The same thing applies to the fan assembly, if it’s available from the aftermarket parts dealer, the quality is fairly reliable. As always, I strongly recommend you purchase the ECM from the manufacturer






P0600- Serial Communication Link Malfunction

P0601- Internal Control Module Memory Checksum Error

P0602- Control Module Programming Error

P0603- Internal Control Module Keep Alive Memory Error

P0604- Internal Control Module Random Access Memory Error

P0605- Internal Control Module Read Only Memory Error

P0606- ECM Processor Fault

P0607- Control Module Performance

P0634- ECM/TCM Internal Temperature Too High

The diagnostics for these 9 P Codes is the same. The only difference between these P Codes is the nature of the error being reported. Unlike the other groups of P Codes, there is no need to break down the difference in failure for these P Codes they all have the same repair: the ECM must be replaced for all of them. There has been an internal failure and there are no other causes

These P Codes all indicate the same thing: an internal fault with the ECM. I won’t bore you with the details of what specifically has failed internally, suffice it to say that if you have one of these P Codes, the ECM must be replaced. The only option for this repair is to visit your local repair shop. The ECM must be programmed with the proper software to function correctly for your vehicle and you must have specialized tools and licensing to be able to download this software, and then program the new ECM. I strongly recommend visiting the manufacture for this repair. The cost will be higher, but the price is definitely worth it. In fact, it’s very likely that even if you visit an independent shop for this repair, they will send your vehicle to the dealer to have the repair done and charge you to be the middle man. They won’t always tell you that this has been done either, I’ve actually seen this happen several times. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The symptoms for these P Codes are very wide ranging. Any system that the ECM controls, which is all engine related functions, could be erratic or malfunctioning completely

Possible causes:

  • The only possible cause is the ECM

Where to buy the parts:

ECM’s are available from the aftermarket parts dealers but I strongly recommend buying from the manufacturer. The quality of these parts from the aftermarket dealers is notoriously poor and very unreliable


P0630- VIN Not Programmed or Incompatible ECM

P0631- VIN Not Programmed or Incompatible TCM

P0632- Odometer Not Programmed ECM

The diagnostics for these 3 P Codes is the same. The only difference between the P Codes is the nature of the error being reported, but it’s only a slight difference. All 3 P Codes are indicating that there is missing information from the ECM or TCM (Transmission Control Module) and the information needs to be programmed into the module for it to function correctly

These 3 P Codes are pretty simple. You will need a scanner that has the capability to program information to the ECM or TCM. For the P Codes that indicate the VIN is not programmed, you simply try to program the correct VIN for the vehicle into the module that’s reporting the error. If the programming can’t be completed or is unsuccessful, the module must be replaced and programmed. For the Odometer P Code, it’s the same idea. You attempt to program the Odometer reading into the ECM. If the programming can’t be completed or is unsuccessful, the ECM must be replaced. I strongly recommend visiting the manufacture for this repair. The cost will be higher, but the price is definitely worth it. In fact, it’s very likely that even if you visit an independent shop for this repair, they will send your vehicle to the dealer to have the repair done and charge you to be the middle man. They won’t always tell you that this has been done either, I’ve actually seen this happen several times. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • There most likely won’t be any observable symptoms for these P Codes
  • It’s slightly possible the vehicle won’t start if the VIN is not programmed into the ECM only

Possible causes:

  • The programming wasn’t completed when the module was replaced
  • The module has failed internally

Where to buy the parts:

ECM’s are available from the aftermarket parts dealers but I strongly recommend buying from the manufacturer. The quality of these parts from the aftermarket dealers is notoriously poor and very unreliable


P0600- Serial Communication Link Malfunction

P0601- Internal Control Module Memory Checksum Error

P0602- Control Module Programming Error

P0603- Internal Control Module Keep Alive Memory Error

P0604- Internal Control Module Random Access Memory Error

P0605- Internal Control Module Read Only Memory Error

P0606- ECM Processor Fault

P0607- Control Module Performance

P0634- ECM/TCM Internal Temperature Too High

The diagnostics for these 9 P Codes is the same. The only difference between these P Codes is the nature of the error being reported. Unlike the other groups of P Codes, there is no need to break down the difference in failure for these P Codes they all have the same repair: the ECM must be replaced for all of them. There has been an internal failure and there are no other causes

These P Codes all indicate the same thing: an internal fault with the ECM. I won’t bore you with the details of what specifically has failed internally, suffice it to say that if you have one of these P Codes, the ECM must be replaced. The only option for this repair is to visit your local repair shop. The ECM must be programmed with the proper software to function correctly for your vehicle and you must have specialized tools and licensing to be able to download this software, and then program the new ECM. I strongly recommend visiting the manufacture for this repair. The cost will be higher, but the price is definitely worth it. In fact, it’s very likely that even if you visit an independent shop for this repair, they will send your vehicle to the dealer to have the repair done and charge you to be the middle man. They won’t always tell you that this has been done either, I’ve actually seen this happen several times. If you want to contact our certified technician with any questions about your check engine light or P Codes, click here. It’s FREE!

Symptoms:

  • The symptoms for these P Codes are very wide ranging. Any system that the ECM controls, which is all engine related functions, could be erratic or malfunctioning completely

Possible causes:

  • The only possible cause is the ECM

Where to buy the parts:

ECM’s are available from the aftermarket parts dealers but I strongly recommend buying from the manufacturer. The quality of these parts from the aftermarket dealers is notoriously poor and very unreliable