How to reset Check Engine light?

[sestivers]

Hi, everyone. My Check Engine light (CEL) in my 2000 LE (4-Cylinder) came on, and I think it was because I did not fully tighten the gasoline tank cap. I tightened the cap and expected the CEL to clear once the fault was corrected. But the CEL remained on and is still on after a couple hundred miles of driving. Was I wrong to think that the CEL would automatically clear once the fault is no longer present? I could be wrong that the gasoline tank cap was the problem, but it would be a strange coincidence if so. I know that I can reset the CEL by disconnecting the battery for a short time, but is there a more proper way to do it? I do not have an engine code scanner, and do not yet plan on buying one.

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[krichardgf]

You don't have to buy one. Go to any Advance Auto Parts store and they have one they'll let you use or come out and do it for you. You can see what the code was and reset it yourself. I did it for the first time a couple days ago. Pretty simple.

[toyomoho]

Also try AutoZone and removing the EFI fuse.

If you go the battery route and the radio has the security code theft protection, make sure you have the code or it is not set.

[diver1972]

It has been my understanding (or rather, assumption) that if the gas cap is the cause of the CEL being lit and the gas cap is either installed properly or replaced (if damaged), then the CEL would dim immediately and automatically. However, I am not certain of this; it is just the assumption that I have drawn after reading owner's manuals on all of my cars over the years.

[toyomoho]

Maybe. The ECU runs through a test of the cars emissions evaporation system (EVAP) under preestablished parameters (MPH, coolant temp, etc). If the problem is solved, the ECU should turn off the CEL. The ECU still needs to run through the diagnostic test to reach this conclusion.

The EVAP system diagonostics has numerious codes that can be set. Without having the code(s) read out there is no way to tell where the problem is or if it is the EVAP system.

Basically the EVAP is tested for system pressure. A bad gas cap equals no tank pressure, however the leak could be some place else, a bad valve, leaking vacuum hose, etc.

Best get the code(s) read.

[sestivers]

So the light did clear on its own after all. It cleared about 250 miles after tightening the gasoline tank cap. I am not sure whether it cleared while driving or whether it was in between ignition cycles.

[toyomoho]

If the CEL does not come back, then problem solved.