I wanted to follow up on this since I had posted about my similar scenario and the solution -- I have put over 1,000 on my Jeep since replacing the charcoal canister with no CEL or gas cap warning chime until yesterday.
Yesterday, out of nowhere, gas cap warning chime started going off and it has been displaying the warning ever since. This morning, after driving approximately 20 miles yesterday with the gas cap warning displayed, my CEL illuminated once again. Obviously is going to be evap related. I'll pull codes real quick...
P0457 loose gas cap, I'm honestly surprised that's the only code...usually it's accompanied with a very small evap leak code.
Gas cap was replaced with both aftermarket and eventually a new OEM when this whole debacle began last year.
Anyway, since I was pulling the codes, I went ahead and loosened then tightened my gas cap back up. Cleared the codes and as soon as I started it back up, gas cap warning chime. So no idea why replacing the canister and literally nothing else made a difference for over 1,000 miles, but it apparently was not the fix. That had me stumped anyway since usually if the problem is the canister it's due to no flow and I was able to blow through the canister with zero resistance. It's also odd that it is detecting such a massive leak, yet multiple smoke tests have shown no leaks in the system and both my little smoker and my buddy's smoker were able to build up pressure in the system while testing.
