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CEL with no Errors reported?

By tbailey264, April 30, 2019

I have an 05 Corolla, and a few weeks ago the check engine light came on. I checked the oil and realized it was low, so I filled it up. Light stayed on. I figured it just needed some time for the sensor to catch up, so I didn't worry. A few days later the light was still on, so I took it to Advance since they do a scan for free. Their scan found no errors, even with the engine on. Any idea what this could be, or how to resolve it so that I don't potentially end up ignoring an actual problem?

  • 110 posts

Maybe disconnect your battery, then reconnect it. That will ensure no residual electricity is in car.

Modern cars have always on electricity for computer (hence fires seen with BMW, etc.) and other components.

Hopefully that will help, since there is no code.

  • 320 posts

There might be a code Advance can't read, but a dealer can...? Usually that would be a transmission issue. A few people have said that their check engine lights go on and off, and years later it still does so...

But if you give it a week or two, it may well go off on its own.

To reset it now, shut the engine, push the odometer button while you turn your key to Run (not Start), wait for a beep, wait five seconds, then start the engine—all while you're pressing the odometer button.

That's the theory, anyway. Advance can also reset the light.

You may want to get a cheap OBDII reader — in the long run it's worth $20-$40 to be able to see codes and reset them yourself. (Some readers just read, others reset.)

I hope it isnt a trans issue, although it very well could be. The car started droning very loudly as well- maybe thats related?


I'm just trying to avoid paying top dollar at the dealer, and I'm worried that once they have my car they might try to insist I have to pay for random things that may or may not work

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