My check engine light has come on twice in the past few days. I took it to Autozone and they checked it (and cleared it) with their little machine. They said that the code was for my gas cap being loose. I've checked my gas cap and it's secure. Any idea what else could be causing it? This is on an '03 QC 4x4 4.7 automatic. I'd hate to think there's anything seriously wrong since I have less than 30k miles on her.

 

why are you taking it to Autozone instead of the stealership? You're still under warranty...

 

I bought the truck used and I'm under the impression that I only had 30 days to transfer the warrany. I didn't know this until I read it here.

 

The rubber seal around the gas cap that makes contact with your tank could be letting air through. My old truck (2000) dakota had that problem bought a new cap, and never had that problem again. Just get a new cap and it will probably fix your problem. Even locking caps are like 10 bucks so it's an easy cheap fix.