Check Engine Light

The Difference Between Stored vs Pending Codes

Mike Cross
Updated Aug 31, 2021
The Difference Between Stored and Pending Codes

You’re driving down the road and everything seems to be smooth sailing, and then “Oh, no!” Why's my check engine light showed up on your dashboard? There are so many different meanings of different symbols and this error is a new one.

So you take your car into an auto shop to have it diagnosed. The test they run gives a series of codes that most likely seem Greek to us, but the codes help determine what is causing an issue with your vehicle.

What do the codes mean and how are they interpreted?

The Difference Between Stored and Pending Codes
The Difference Between Stored and Pending Codes

What Are Codes?

Running diagnostics on your vehicle does not guarantee an automatic resolution and diagnostics do not typically just spit out a simple answer. Diagnostic codes are a complex system that allows diagnostic devices to give basic diagnostic options. At times, they may be spot on while at times it becomes a bit of a guessing game.

It is possible for you to determine on your own what the diagnostic codes mean. You will still have to have it tested for codes. The mechanics will typically provide the codes to you and you can do your own research on them if you please.

Keep in mind that interpreting the codes can sometimes be confusing, but it is doable. Mechanics have noted that they find translating the codes difficult at times as well due to the complexity of the code system.

Stored Codes

There are some codes that are required by law to be stored on a common code list for manufacturers. These are standardized, stored codes. This means that a specific code that is on the standardized list would mean the same thing for all vehicle makes.

However, not every stored code is a standardized code set. There is a unique format for the way the codes are set up, which we will get into a bit later. A stored is a code that your vehicle generates and stores until the error is corrected and cleared.

How Can You Clear Stored Codes?

Reading the error codes
Reading the error codes

If you fix an error related to a specific code and then your check engine light comes back on, it means the error you corrected was not related to the code causing the light. Your check engine light could have multiple stored codes of basic malfunctions and you could potentially be working through a series of checks to narrow down to one code.

  1. Fix the error code. I know this seems like it might be a basic suggestion, but it’s the best place to start. If your vehicle has multiple codes causing that check engine light to come on, you may have to fix multiple codes to get the light to go off.
  2. Learn the Code Meanings. If your vehicle has multiple stored codes from errors, it is possible that some of the diagnostic codes do not apply to the malfunction you are specifically trying to correct. Try to interpret each code and narrow down the code to your specific issue.
  3. Be Prepared. Know that if you are working through a list of diagnostic stored codes, you may end up incurring a significant expense. In order for a code to be cleared, the issue has to be fixed. When you run diagnostic testing, you may discover stored codes that you weren’t even aware of an issue for.

Pending Codes

Pending codes do not turn on a warning or check engine light. The code is an indication that something is not firing correctly within the mechanics of your vehicle, but the error is not yet an issue for your vehicle.

Pending codes could be a one-time glitch that triggered from something unusual, or they could mean that a sensor malfunctioned or was just out of normal range temporarily. While pending codes might be an indication of a future problem, they are not anything that needs immediately addressed.

When Do You Heed a Pending Code?

Most often, pending codes are primarily irrelevant. This does not mean you should completely ignore them if you are trying to diagnose a specific issue, but you should understand that if you are working to clear a specific error or light, the pending codes are not associated with that error.

A pending code very well could be a warning sign that something is beginning to malfunction. It is meant to make you aware, but it’s not triggering an alert. If you are running diagnostics and note repetitive pending codes it would be a good idea to dig into that code, as there may be a simple fix before something bigger goes wrong.

Understanding the Codes

Codes are issued in an alphanumeric format that is five digits long. Typically, the first sequence is a letter and the remaining five are numbers.

  1. Digit 1 The first digit will signal B (Body code, including A/C and airbags), C (Chassis code, including ABS), P (Powertrain code, including transmission and engine), or U (Network code, related to wiring). P is the most common code in diagnostics.
  2. Digit 2 The second place is either 0 for generic OBD code or 1 for vehicle manufacturer code. If your code includes a 1 as the second digit, it is manufacturer related and you should check for recalls first.
  1. The 3rddigit is any number between 1 and 8. These cover various specific topics such as fuel metering, ignition system, and transmission. Each number has a specific representation.
  2. 4 & 5. The last 2 digits are the fault description codes. This is where it can become the most challenging to interpret the code. These codes are much more detailed and vary immensely.

Final Thoughts

Codes can be quite overwhelming. The specific difference to remember in stored codes and pending codes are the stored codes are what trigger failure or check engine lights and they are the codes that need to be addressed.

Don’t let your codes get you down! Hopefully this is helpful to you as you get started interpreting your diagnostic codes.

Mike Cross
Life is too short to drive with stock audio

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3 comments on “The Difference Between Stored vs Pending Codes”

  1. TY. will the codes clear themselves once corrected, or must one clear them with a scan tool?

  2. My scan tool started at c a n o b d 2 then scan PMW then scan kwp 2000 then the iso 9141 protocol after that it just goes right back to c a n o b g 2 not giving me a code and not telling me there's no code what should I do?

  3. I was told by a Reputable Certified Mechanic shop that to
    drive with No Stops for an entire hour or two After codes where cleared after -mechanical work -
    to Reset the Computer

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