"Check Gas Cap" (Driver info center)

[MajorsSerj]

Hello All.

I have 2003 SLE and recently have received the above message (check gas cap) in my D.I.C. Which I have and ensured that it was tight and past the normal three "clicks" it needs. Is there a reason for this message To reappear after a cold start? I live in the Windy City so I don't know if temperature has a factor in This or if the gas cap (original cap) has failed? Any help is greatly appreciated. Thank you!

[nos4blood70]

Check the lip on the fuel filler neck, it may be corroded and preventing a tight seal. Sand it down or hit with a scotchbrite pad to clean it up. If the issue persists, you can replace the cap.

I had this issue along with the Check Engine Light P0442 for small evap leak. In my case it was caused by the fuel lock ring gasket in the trunk which I must have messed up after changing the fuel level sender.

[Archon]

If the sanding doesn't solve the problem, add a bit of silicone grease around the filler neck, and see if that helps.

[maxi426]

Check Gas Cap can indicate a leak anywhere in the EVAP system. Rust on the sealing surface of the filler neck is possible as well as rust under the metal area of the plastic tube.

[96 SSEi]

the rubber gasket in cap gets hard so only put on cap until it hooks. dont go for clicks. worked for me.

after you sand, and before trying silicone, put a thin layer of clean engine oil on the lip sealing surface.

[imidazol97]

The error will clear when the computer runs a vacuum check and the car passes that test. There are other ways the light can clear, but that's the best one. The tank has to be roughly between 3/4 and 1/4 on the fuel gauge. The engine has to be luke warm, such as after a short drive and it's turned off for a stop. Then restarted.

I believe I had a problem where the check engine light kept showing a leak in the tank system and I checked the rubber lines on the front of the engine from the tap into the throttle body to the U-turn and then to the poly line that goes to the back of the car to the tank. Along the front of the valve cover is the purge valve. I found a crack in the U-shape rubber part which leaked. I believe that was causing the computer to sense a leak. I covered the part with shrink tubing to reseal it.

Your leak may be elsewhere than the gas cap and seal. I had started there in my troubleshooting.

[Kevin Amstutz1]

Look at the fuel cap oring, they get cracked.

[MKMike]

...and, if needed, they're inexpensive.
Genuine OE ACDelco cap is just over $16 at Amazon and cheaper at Rockauto.

[Namrepus28]

I replaced my gas cap with a new one and it cleared my code. My O-ring was old, dry, and cracked.

[MajorsSerj]

Thank you everyone for taking the time to respond on this matter. I took the approach with the Scotch Brite Pad and it seems to have eliminated the message from appearing in the DIC. If it persists, I will troubleshoot the other methods/suggestions you all mentioned as well.. Have a wonderful weekend!

[redfury]

I had this problem as well. New cap, tried lubricating the O ring, sanded and painted the sealing surface with POR15...it still came back. I ended up having to replace my Plenum after blowing it up this winter and discovered the Rubber connection on the throttle body that connects the fuel pump regulator and the purge valve was split. There's no off the shelf replacement, other than the hard plastic lines and the rubber piece for 30 bucks, so I repaired mine with a big piece of shrink wrap and some liquid tape. Haven't had the code or light come on since. Easy to overlook, but it's a common failure due to age, so take a peak at it if the problem comes back.

[Jason H.]

I had the same issue (I am down in Joliet) and the metal lip that the gas cap sealed against was rusted and pitted. After trying to clean it up and replacing the gas cap, itself, it still didn't work. I wandered through a boneyard until I found a filler neck with a good, rust-free lip on it and yanked it. Once I had it installed, I started the car and my light went out. Mind you, this was a light that was the bane of my existence for a couple of years and sent me on a wild goose chase replacing valves and sensors all over my emissions system. With the new(er) neck, I scotch-brite the lip and shot three light coats of clear on it to try and prevent any rust from rearing its ugly head.
*****BEWARE*****when looking inside fuel doors to check the condition of the necks, watch out for wasp nests!! (if you wait until it's a little warmer out). I did mine last summer and was surprised by a nest in the first three that I opened! Scared the *shoot* out of me. If you are going to check now, I imagine you will be ok...
Good luck! Hope this helps.