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