I have a 2005 Accord V6 that I purchased in July 2016. Unfortunately I had my first check engine light this past September, have spent quite a bit of money trying to fix it, but it keeps coming back. The Power Train System has Code P0497 and Secondary DTC P0455. The first shop I brought it to performed a smoke test and checked the purge valve. The mechanic could not find any obvious problem, but said if it was his car he would replace the purge valve. I paid to have the purge valve replaced and the check engine light went away for a couple of weeks. It came back with no noticeable change. I then replaced the gas cap with a non-OEM one from Amazon and the light stayed on. I then brought my car to a different shop where the mechanic ran "a 20 minute scan", found no issues and cleared the code. The CEL was off for a few days then I started getting "check fuel cap" message in the dash display. I removed and retightened the gas cap. This message went on for a couple days then the CEL came back and has stayed ever since.

The car does seem to shudder/stumble occasionaly at lights, no change in RPM, feeling like it's going to die but thankfully it does not. I had not noticed it for a while, then filled up with gas and had it on the way home. Any helpful information is greatly appreciated.

 

you have a leak somewhere in the EVAP system. Look up the codes. If the engine is not showing any sign of smoke leak, then it has to be somewhere else. Replace the gas gap with an OEM. While your there, look at where the cap sits on the gas fill, does it have any rust or crud build up. Check the fill neck its self (under the car and behind the fender. Ive had rubber hoses degrade at the evap port on the fill tube.
Im still learning new honda ( last one was a 1995 civic) so I guess we will learn together
good luck