Check engine light - on Apr 1.1 and downpipe

[isaidsthats]

That was the other piece of missing information I meant to point out.. it sounded like he had his downpipe on for a while, which would make it seem strange that he would not have experienced a CEL relating to emissions before.. Maybe that was just unclear in his first message, but I got my CEL and wasn't surprised by it, within a day after running aftermarket downpipe with stage 1.5 tune..

Thank you for your insight! I had my dp since 3500 miles and the cel came on at about 8300 miles. It was advertised by AWE that their catted dp was guaranteed not to have a cel but it could be false advertising. I plan to get the codes soon but for now I drive my little civic.

I just remembered, I was in jersey and in that state you can't pump your own gas. I left the engine on while he was pumping... But that was 2 fill ups ago.

 

[PRND[S]]

Leaving the engine running while opening the filler WILL produce a emissions CEL.

The car pressurizes the gas tank shortly after engine start to check for leaks. The idea is to catch hydrocarbons from improperly sealed gas tanks getting into the atmosphere -- that used to cause a substantial percentage of air pollution. The car detected a pressure drop while the engine was running and interpreted that as a leak, rather than someone refueling with the engine running.

You also will not pass smog testing in places like California if you have an aftermarket gas cap for this reason. I had a truck that failed the visual inspection because I replaced the OEM non-locking gas cap with a locking one.

 

[isaidsthats]

Leaving the engine running while opening the filler WILL produce a emissions CEL.

The car pressurizes the gas tank shortly after engine start to check for leaks. The idea is to catch hydrocarbons from improperly sealed gas tanks getting into the atmosphere -- that used to cause a substantial percentage of air pollution. The car detected a pressure drop while the engine was running and interpreted that as a leak, rather than someone refueling with the engine running.

You also will not pass smog testing in places like California if you have an aftermarket gas cap for this reason. I had a truck that failed the visual inspection because I replaced the OEM non-locking gas cap with a locking one.

The cel came on after 2 fill ups, would it go away after time? Would there be a different warning light for this as well?

 

[PRND[S]]

I would expect that CEL to come on immediately if there is a pressure drop with the engine running.

Some DTCs (Diagnostic Trouble Codes) clear themselves after a configured number of drive cycles where the problem doesn't occur -- that number (and the remaining drive cycles until it clears) are visible in VCDS. I'm not sure if the pressure drop CEL is one of those, or how many cycles it takes. That's the reason why I don't like blindly clearing codes just to make the idiot lights on the dash turn off, you should really see what the code is for first.