Thread: Dic keeps saying to check gas cap even after replacing the gas cap

So, as the title says, my dic said to check gas cap, so I did what anyone would do and replaced the gas cap with a new one. Well it still keeps telling me to check the gas cap. It's getting annoying having to hit the enter/reset button every time I start the car. Anyone run into this issue and know a solution?

It's an 04. OK, I'll have to look into that.

Had a gas cap code on my 04 , replaced it with this one and it has not come back.

http://www.amazon.com/ACDelco-GT279-...ype=automotive

Ok, so I replaced the cap with the one rottonj recommended and it still keeps saying check gas cap. Once a a great while it doesn't tell me to check gas cap though. Where should I start looking for an evap leak?

Do a YouTube search for home-aid smoke test, or bring it to someone with a tester.

I think this is usually a bad evap canister, it was on mine. You might need the sub-harness that comes with it as I believe they switched the electrical connector on later models. I got the damn canister for cheap on rockauto and it cost me as much for the harness at autozone when I realized I needed the harness. Try checking that maybe. Too easy to do, rear tire off, splash shield off, its right there.

Was it the canister or the canister purge valve/solenoid? I have no experience with emissions equipment except eliminating it on older cars.

Its the vapor vent valve/solenoid. This guy

http://www.amazon.com/ACDelco-214-23.../dp/B00559WHSE

Also note you will need the new harness as well.

http://www.amazon.com/gp/product/B00...7EBKDS8BGHDB92

I believe there was a design change after '04, much like with the fuel filters going from external to internal or integrated into the fuel pump. I would air on the side of caution and buy the harness as well. It might say it doesn't fit an '04 but ignore that. The vent valve/solenoid is a newer design hence the requirement for the harness. I was unlucky enough to take of the left rear tire and splash shield, take the valve/solenoid off only to realize the plugs didn't match.

Its an easy install, buy both and even if I'm wrong about the harness worst is that you return it. I think its horse sh*t that the harness costs just as much as the valve/solenoid, but whatever. This should fix your problem.

All I had to do was stick my dic in my gas cap and it fixed this problem on my 04.

Originally Posted by mguzzo

or you have a pinhole leak in the filler tube between the cap and the tank

I know it's not this. I fill the tank until the cup where the cap goes is full. Well I did until 2 weeks ago anyway. Now I found out that's a bad thing.

Thanks robinsone. Parts ordered.

Update: finally got a chance to install the canister and wire harness. No more engine light and dic message. Thanks everyone.

Maybe this is a little late, however I had this same "Check Gas Cap" issue, I replaced the cap and the light stayed on, I believe that was the same code, I chased a few different EVAP sensors, and then I found it, being the 'EVAP Vent Solenoid/Purge Vent Solenoid' (something along those lines) underneath the rear bumper, on the left hand side. Look under the car and straight up near the gas filler neck and you'll an odd, soda can sized plastic canister, I replaced it and cleared the code. Never came back this was on 10/02/2016 @ 192,141miles.

So I had a evap code from the 08 cobalt I had and it uses the same gas cap as my 07 (no actual thread more of a bayonet lock). The seal on the cap is important as the car will pull a vacuum when running. The gas caps seal was not broken but it was heavily worn and lost all of its spongyness. I bought a replacement gas cap and the problem disappeared. I imagine the one on my GP will have the same fate but it is a cheap and easy fix.