The check engine comes on and goes off intermittently. Because it was not on when the situation was checked the diagnostic scan did not show a problem. I have noticed that the gas cap has been extraordinarily tight on two occasions and after the car was refueled, the light went out when it was supposed to when the car was restarted. Today the light came on, but the cap was just normally snug. The car has been scrupulously maintained. It is a 2001 model with 145,000 on the odometer. No other problems are evident.
When the CEL comes on, a trouble code is recorded in the computer, even if the light goes off. Most chain autoparts stores will read these codes for free. Find out what the code is and post it back here…It will be something like P0123. There may be more than one…
That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.
Apparently the capabilities of the code readers used at auto parts stores varies a lot. I have yet to find an AP store in my area that can pull any codes unless the light is on at the time. They will also say this to you, and won’t even come out to the parking lot to give it a whirl if the light isn’t on.
In other words, many of the generic code readers only read current codes. You, however, should have “history” codes. You might just need to pay a shop a fee to have the codes read - but you need to know that their equipment pulls history codes.
DYI and save…
I already did. I got really tired of it all.
Sometimes (not always, granted) the dealer will read them for you - for free.
Their reasoning is that if you’re coming to them, you’ll buy your parts there. In some cases, that’s true. Most VW and Toyota dealers will (that’s what I own now). I’ve done it a couple times, once to figure out a fault, and another to make sure it didn’t have any stored.
Give that a whirl…the worst that can happen is they say no.