MellonC00

did you know that an old gas tank cap can throw off a CEL? I didn't know that. Apparently an old one (16 years old on mine) can have the rubber part become hard and dusty and not shut the air passage into the gas tank 100%. I replaced it with a $20 part from a Lexus dealer ( a local greedy dealer wanted $50) in AZ and the CEL went away without even my resetting anything......

So, if your gas cap is old, I'd recommend you check it out too. A simple fix.

salimshah

Based on where you are, the annual safety/emission test ... emission test really, requires the gas cap be tested.

Gas cap failure is so common that when CEL comes up, most folks suggest replacing the gas cap, even without investigating the error code.

After market gas caps are around $10 and from dealer, you can expect one for about $40+. The OEM O ring/gasket can be purchased for about $13


Salim

maxSteel

I tried an aftermarket cap when I was getting the canister code. I found it very hard to remove, like there was a vacuum seal.
Switched to a Toyota one, no problems.

MellonC00

Interesting. My mechanic told me the same thing that you should use the OEM for the gas cap. I guess non OEMs don't have as tight of a seal.

glenn2623

I had the various Trac Off, Check Engine light, VSC lights on with a bad gas cap gasket. Ordered both a replacement gas cap from Rock Auto and OEM gasket. After replacing the gasket on the OEM gas cap the codes did not clear after 140 miles or so. Anyone know how long it takes for the ECM to clear the error codes. I dd the battery disconnect about 10 days ago and cleared the codes. Got terrible gas mileage, first tank was 10 mpg, secondary to the clearinging of ECM data with the battery disconnect. The background research on ECM data dump after a battery disconnect looks pervasive across the car industry. I'll be a little less prone to disconnect the battery the next time.

OilMemes

It would be most kind of you and very appreciated, if you can start a new thread with your issue instead of reviving one from 3 years ago.
But let me ask something, did you at any point get the actual fault code pulled from OBD? Which code number was shown? If replacing the fuel cap did not stop the Check Engine light coming on even with 140 miles of driving, I have some suspicion that you do not have a Gas Cap fault code at all.
Do keep in mind that the OBD readers in common use nowadays, allow you to clear the Check Engine codes without deleting the ECM computer data. So that is something to remember for the next time something like this happens.