Ok so my filler cap light comes on when I start driving. I have checked both the gas cap, the engine oil cap and any other caps I could find and have tightened them so that they are not loose. The problem doesn't seem to go away.

Any thoughts, advice?

 

The light refers to the fuel filler. A nice touch because in most cars the "check engine" light will come on.
I'd check the fuel cap again - of course the whole point of the light coming on is to alert you to a vapor leak from the fuel system so you may what to check for any damage to the filler cap (out or round) or other fuel system issues.

 

Could the cap go bad? (like a failed seal?)

 

Yes caps can go bad. Like a failed seal.

 

I've checked the fuel cap few times and nothing seems out of norm. I have opened and closed it tight few times as well. However, I'm starting to think that it could be that after a while when you drive the car it looses that sealant grip or something. I will have to have the shop take a look at it and check it out. Not sure if anyone would actualy know if it's bad just by looking at it.

Any other thoughts? Oh, and by the way, my check engine is on due to the 180 thermostat the shop installed for me. It's something that won't go away unless I change it back to stock.

 

My check gas cap light was on due to a bad fuel canister (something thats attached to the fuel line and system) Theye replaced it and whammo, no more issue

 

If you have changed accessory belt recently just above alternator is your fuel tank vent, check lines and make sure did not put upside down. Lines fit better upside down but the electric connection actually goes on bottom. If upside down or lines loose the light will come on.

 

Andy, U R da MAN!! I have been dealing with this for a While!! When I replaced my Supercharger, Of course this was off and It never occured to me that I could install this USD! Man 0 Man! U saved my life because this was starting to wear me out and needing to go through Inspection in the next 30 days I was getting to the point of disconnecting the Idiot light because they only look at the IM Monitors and all of them will read OK even though there are 2 codes showing.

Thank you!

 

Had this light come up today after a top end rebuild followed by some supercharger shenanigans. Exactly right on the flipped purge valve. Fixed it in a wegmans parking lot in 2 minutes. Nobody's perfect I guess.

 

My light was coming on after an alternator replacement. Just found this page, went out and looked and mine was upside down as well. Good info. You gotta love this forum.