Pending Code vs Trouble Code in OBD2 Systems: A Comparison

Pending code vs trouble code in OBD2 systems can be confusing, but understanding the importance of the OBD2 system when it comes to diagnosing car issues is important, and this begins with recognizing the differences between pending codes and trouble codes.

Pending Code vs Trouble Code in OBD2 Systems: A Comparison

Both past and current codes are stored in the OBD2 system, and we’ll highlight the differences between them so you can know what they mean and how to interpret each code.

Features Pending Codes Trouble Codes
Function Pending codes serve as an indication of a persisting problem. They are mostly logged by the computer, even when they don’t get to a threshold. Trouble codes serve as an indication of a problem that occurs intermittently. They trigger errors and are shown in the light of the dashboard.
How to check Code readers designed to read pending codes Code readers are designed to read trouble codes.
How to clear Clearing the code is done with a reader, but this is after fixing the issue. The codes are cleared by fixing the issue and using a reader to clear them.


What’s the Difference between Pending Codes and Trouble Codes?

The main difference between pending codes and trouble codes is the way the OBD reader displays them. When pending codes are displayed, it’s an indication of persisting trouble. On the other hand, trouble codes serve the purpose of notifying you that there is an issue with the vehicle.

Basically, the computer logs the pending codes, but these codes don’t get to any threshold. For instance, in a situation when a fault in your oxygen sensor occurs, the problem won’t be registered on the computer until after some time. The code will remain pending during this time.

On the other hand, trouble codes trigger error signals almost immediately, and this causes the light on your dashboard to come on. It’s important to always identify and solve more serious problems whenever you identify these problems. In addition to what each code means, there are other differences to note, which include the following:

– Checking the Code

One of the most obvious differences between the two codes is how you check for each code. Most people will tell you to use a code reader, but these readers mostly read trouble codes. Checking codes that are pending requires the use of a unique OBD scanner with access to the live data feed of the computer.

With the right scanner, you only need to connect to the diagnostic port, which is below the dashboard. After the connection is established, all you need to do is follow the instructions brings. On the other hand, you can use a simple reader to check for codes that are stored, and this also requires a connection to the diagnostic port, which is below the dashboard. Once this is done, you will be able to see the trouble code and what it means.

– Clearing the Codes

Apart from knowing how to check for each code, it’s also vital to clear each code. Clearing codes that are pending converts them to trouble codes, especially when the problem doesn’t stop. However, after resolving the issue, all you need to do is use a read to clear the code.

This also requires connecting the reader to the diagnostic port. The main thing to always have in mind about the process is the possibility for the codes to come back, especially when you don’t properly resolve the issue. Fixing codes that are stored also follows a similar process, and you can use a reader to clear the code after it has been fixed. Codes that are stored can also return if the problem is not resolved properly.

There are codes that are installed on the computer of your engine just to meet emission and safety requirements. Another thing to note before clearing the codes yourself is that in some places, doing it yourself may be illegal. Therefore, it’s important to verify the legality before clearing the codes yourself.

– Identifying the Different Codes

Trouble codes, pending codes, and other codes are usually presented in a five-digit alphanumeric format. Basically, the first letter digit is a letter, and the remaining are numbers. The first digit can be B, C, P, or U, and it’s important to note that each of these digits has its meaning and represent different signals.

Signal B represents the body code, which includes airbags and AC. C represents chassis code and ABS, P represents powertrain code, which includes engine and transmission, and U represents network codes, which are codes that are related to the wiring of the vehicle. Among these codes, P remains the most common diagnostic code.

The second digit is either 1 for manufacturer code or 0 for generic codes. Therefore, if your code shows 1 as the second code, then it’s an indication that the fault is manufacturer related. The third digit usually lies between 1 and 8, and this represents different aspects. This includes transmission and ignition systems.

The fourth and fifth are the last two digits, and they are basically fault description codes. In most cases, interpreting the code can be rather challenging because the codes vary greatly and they are more detailed.

What Are Pending Codes in OBD2?

Pending codes in OBD2 are a preliminary investigation of the vehicle’s engine. Basically, they are not severe, but that doesn’t mean that the codes should be ignored. Checking for these codes is mostly done with the help of a reader that is designed to pull these codes.

Functions of Pending Codes

These codes don’t turn on the check engine or warning lights on the car’s dashboard. They are basically an indication that a mechanical component of your vehicle is not operating or firing as it should. However, in many cases, the error causing this misfiring may not already be an issue of concern.

While pending codes should not be ignored, they are mostly a one-time glitch that arises from an unusual event. This could also be a result of sensor malfunctioning or basically anything out of the normal range. However, the main thing to note about codes that are pending is that they are a potential indicator of a future problem, which is why it’s vital to pay attention to these codes.

– When To Pay Attention To Pending Codes

As mentioned earlier, codes that are pending don’t always mean anything relevant, but it’s not a ticket that you should overlook them. A key thing to understand, especially when diagnosing an issue, is that codes that are pending are not usually associated with light or other specific errors.

Pending codes are also a sign showing that a malfunction has started. Therefore, it’s important to be aware of these codes and understand that they don’t always trigger an alert. When you perform a diagnostic on your vehicle and you notice that a pending code continues to appear, the right thing to do is to investigate further into the code. There are many simple fixes you can do to handle this type of issue.

What Are Trouble Codes in OBD2?

Trouble codes in OBD2 are codes that the system of your vehicle provides. These codes are usually for safety precautions, legal purposes, or a potential indication of a malfunctioning in your vehicle. These codes are also detected with the aid of a reader designed to identify trouble codes.

Trouble Codes in OBD2

There are certain codes that the law requires to be stored on a manufacturer’s code list. These are also known as standardized trouble codes. Basically, a code that is on the list would be the same for all vehicles.

However, it’s worth noting that not all trouble codes are standardized. The setup of the codes is in unique ways. Basically, vehicles generate these codes and store them until they are cleared or when the error is corrected.

– Clearing Trouble Codes

After fixing an error that is linked to a code, and you notice that the sign comes back on the check engine light, it’s an indication that the correction made was not related to the code that caused the light in the first place. This is because there are many trouble codes that could be linked to the check engine lights, and this could also be potential indications of basic malfunctions.

There are processes to go through to determine the right code for the malfunction and fix the issue correctly.

  • Fix the error code: For many, this might only be a basic suggestion, but it’s the starting point for everything. If there is more than one code triggering your check engine light to turn on repeatedly, you’ll need to fix the different codes before the light goes off permanently.
  • Learn the meaning of codes: If there are more than one code causing the errors, it’s like that certain diagnostic codes may not apply to the malfunction or issue. Apart from fixing all the different codes, it’s also important to know the meaning of the different codes, so you can easily narrow things down and determine the specific code causing the issue.
  • Be prepared:  A key thing to have in mind, especially when using a list of diagnostic codes, is that the expenses involved might be on the high side. Therefore, to clear the codes, you’ll need to fix the issue. It’s important that you are prepared ahead of time because you are likely to see codes you didn’t even know of when you run the diagnostic testing.

What is the Difference Between a Pending Code and a Trouble Code in OBD2 Systems?

In the realm of OBD2 systems, understanding the disparity between a pending code and a trouble code is crucial. The former refers to a potential issue identified during the diagnostic process that has not yet met the criteria to become a confirmed trouble code. On the other hand, a trouble code suggests a definite problem that must be addressed. Delving into the technicalities of these codes can help you better comprehend the workings of your vehicle, such as the ram promaster 4×4 and awd explained.

Is a Pending Code Related to a Bad Fuel Pump in OBD2 Systems?

A pending code in OBD2 systems may indicate a problem with the fuel pump, such as starting car with bad fuel pump. While it doesn’t guarantee a faulty fuel pump, it could be a possibility. It is advised to diagnose the issue further to determine the exact cause and take necessary actions for repairs.


OBD 2 scan tools are one of the most useful tools for anyone who owns a car because they are used in checking for both the pending codes and trouble codes. A proper understanding of these codes is vital because it will help you save time and money in the long run. In this comparison guide, we have provided the differences between the two engine codes, how to check them, and how they are cleared.

The main thing to remember is that pending codes are codes that haven’t gotten to a threshold, even though they are logged on the computer. On the other hand, trouble codes are indicators of an error that has been triggered, and you can see this error indicated on your dashboard.

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