A couple of weeks ago, the gas cap warning message on my 5.4L showed up on my dash. Didn't think too much about it, figured to get one next time I was at auto parts store.

Then, a few days ago, the CEL came on. But truck seemed to run fine. As I was about to leave on a long trip this morning, I had the codes scanned just to be safe, and as expected, it came back with only the gas cap code. I was running late, so I just drove (yeah, yeah, I know). The CEL is still on.

I've also felt it hesitate a few times when the rpms got down to about 1200 (going up a hill pulling a trailer). Didn't think much, my diesels always did the same thing.

Well, tonight, a few miles down the road after I filled up a nearly empty tank, the CEL flashed for a few seconds, then quit, but still on.

Can all of this be about the gas cap? I saw some talk about fuel pumps, misfiring and catalytic converters getting ruined on here, but it seems like it could all be fuel related, and the gas cap might be the culprit.

 

There have been cases where the gas cap has triggered a CEL that corresponded to an evap code. Sometimes it has been that gas cap was not on or not tightened all the way. There have been cases where the gas cap has need replacing.

It really depends on what the code is and tracking it from there. I would see if there is a stored code that could give you a better idea of what tripped the CEL. Hopefully if the code is stored that will give you a better idea of what transpired

 

Get and post the EXACT fault code(s), they will provide guidance.

Ambiguous semi-definitions of the fault are not useful.

 

Well, following a suggestion I found on an old thread here, I flipped the gasket over on my gas cap, disconnected the battery for a few, and now after driving about 600 miles and filling up a couple of times, the CEL has never come back on or flashed. Not sure what all that was about, but if it happens again, I'll capture the codes.

 

Whenever you put fuel in the truck, ALWAYS twist the gas cap until it clicks at least 5-6 times. This will ensure that it is tight enough. If the code reappears in the future, it might be time to replace the fuel cap. The gaskets do dry out & crack over time.

 

Can the gasket be replaced?