Cadillac DeVille Problem Report
Cadillac DeVille Check Engine Light Due to Gas Cap Issue
Illumination of the Check Engine Light can be caused by a loose or worn gas cap.
Code came up with very small vacuum leak in evaporator system or also Check Gas Cap. I originally fixed the problem by dabbing a small amount of grease on the rim of the gas filler neck. But after a year or so I finally figured out the problem. The gas cap is a poor design. I tore apart the gas cap and found out the seal that is really a like a rubber grommet does not contact the rim of the filler neck properly. I took a piece of single strand copper wire and wrapped it around the back side of the seal (side closest to the handle of the cap) forcing the seal closer to the rim side of the filler neck. Problem solved. RRH - Visitor
Dealer wanted $79.50 for a new cap. Autozone $12.00 - Visitor
I got the warning. I took the gas cap off, cleaned it and applied some light silicon lubricant and the problem hasn't come back in a couple of years now. I did NOT replace the cap... just cleaned it. - Visitor
I have replaced the gas cap twice without eliminating the problem - Visitor
Not fixed, needs new gas cap, needs so much stuff, this is small. - Visitor
Service engine light on and evap code. Both (99,400 and 14,300)times resolved with new cap. Seems like cap should last longer. - byrnin
check gas cap comes on on the dash replaced cap 3 times still comes on have reset computer everytime - Visitor
appears that after it rains the Check Gas Cap sensor goes on.. Thinking it's a Sensor issue - Visitor
I replaced the gas cap and it is still and issues. I suspect there is a vacuum leak somewhere around the gas tank. - Visitor
Tightened gas cap and the light eventually went off. - Visitor
Problem not yet resolved. Will probably have to replace cap - Visitor
had to buy new fuel cap. then had to wait two days for sensor to register the new fuel had been installed before light went off. - Visitor
replaced cap multiple times from dealer. finally they must have felt sorry for me and told me to clean the cap really well...toothbrush & water...dry well with lint free cloth. It worked!!! have to do about every six months as error codes starts again. Still doing @ 102,000 miles...looks like they would have fixed this by now!!!!! - Visitor
Check Gas Cap displayed on 'info'. Tried tightening cap several times, light came back as soon as I started the engine. Saw on another forum that the cap may need replacing...will attempt that as the first option. - Visitor
Replaced cap. - Tess03
Happens by accident (my wife or kids) all the time...always make sure cap is tight when you are done filling the tank. - Visitor
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