[Starship]

I got my first CEL with P0442, "Evaporative Emission Control System Leak Detected (small leak)." There was no "CHECK GAS CAP" message in the DIC and thus I thought it was something serious until I hooked up the scanner. It looks like my locking fuel cap CST 5903 is the culprit (it obviously couldn't be me). I wonder what would actually trigger the "CHECK GAS CAP" message.

 

[Silver LTZ]

I read on the G6 boards back when I had one that some aftermarket caps could cause this.

By the way, you see your user title. :-D

 

[Starship]

The "Technical Guru" bit? The rebel in me is still mulling over a proper retort. I guess I'll have to fact-check what I say more carefully from now on.

 

[Silver LTZ]

The "Technical Guru" bit? The rebel in me is still mulling over a proper retort. I guess I'll have to fact-check what I say more carefully from now on.

LOL, it us just because you are always on top of the tech questions, and I appreciate it.

 

[elcompaLalo]

Hey I like the new title, and we all appreciate how Starship is on the technical stuff.

Thank you sir!

 

[chevyguy8893]

It may take a larger leak detected by the ECM to set the "check gas cap" warning in the DIC. Most of the times the seals themselves on the aftermarket gas caps don't seal properly. If a gas cap is not tightened down completely it would be a larger leak as compared to a small leak past the seal itself. I will say though a majority of small leaks that I have worked with have been gas caps.

 

[Starship]

LOL, it us just because you are always on top of the tech questions, and I appreciate it.

Hey I like the new title, and we all appreciate how Starship is on the technical stuff.

Well, my soft spot is puzzles and I seem to have found a forum I can park myself for a while, so I didn't really need any encouragement.

It may take a larger leak detected by the ECM to set the "check gas cap" warning in the DIC. Most of the times the seals themselves on the aftermarket gas caps don't seal properly. If a gas cap is not tightened down completely it would be a larger leak as compared to a small leak past the seal itself. I will say though a majority of small leaks that I have worked with have been gas caps.

The cap was indeed, ahem, a little loose (it must have freed itself). I was under the impression that any EVAP leak will trigger that message. Anyway, this gave me a fresh perspective on how that little CEL can ruin one's day. It's a good thing I had a scanner handy.