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Computer codes - how long stored?

I see lots of discussion about reading codes and how to erase them, but what about the other side of that question. Once a code is stored in the computer, how long does it stay there? Forever? Even if power is removed? Only through a certain number of engine starts and stops? A certain length of time?



I’m talking here about a situation where the check engine light has come on and then gone out on its own. I assume that, if the light comes on and stays on, the code will of course be there.



Thank you.

I believe the codes remain stored as long as power is applied or until someone intentionally clears them with a scan tool. Even “temporary” problems that cure themselves will leave a record until they are cleared…Disconnecting the battery will clear the codes…

Thank you.

UR Welcome…

Yes. They’re stored forever. With the proper scanner you can look up the history codes.

Tester