"Service engine soon" on and off
 

The "Service engine soon" light came on the other day. I didn't have time to get to Autozone to get the code scanned so I had to wait til yesterday to get it scanned. Well, started the truck and the light was off. Got to AZ and they couldn't get a scan cuz the light was off.

Any ideas on why the light would go off? The guy thinks that it might be a vacuum leak on the gas cap. Could that have been a proper assumption?

Mine did the exact same thing! Will be on for a day or two and then off for the same... went to autozone and had it read and the code was for emissions vapor leak or gas cap. Got a new one and no SES light!

Cool. Thanks. I bought this new gas cap the other day from Meijer and it is one of those, leave it in and forget it, things. The cap has a hole with a spring loaded stopper that keeps me from having to take any gas cap out. Well, I'm guessing it's not working out to well. I'll have to return it and get a different one.

Thanks leeroy74.