A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Cadillac Eldorado Check Engine Light Due to Gas Cap Issue
Cadillac Eldorado Problem
Average Mileage: 70,751 mi (60,000 mi - 81,502 mi)
Visitor, 1998 Cadillac Eldorado, 60,000 mi
The onboard diagnostic system gave me a check radiator cap notice. I check the cap and it was screwed on firmly. Apparently the cap is getting worn and it intermittently compromises the "Closed system". I have not had to replace the cap yet and the light has not come on in quite awhile. Until it comes on and stays on, I'll keep the old cap.
Visitor, 1998 Cadillac Eldorado, 81,502 mi
Engine code is diagnosed as a gas cap problem several previous times. However, the last 2 times this has happen a new gas cap from the dealer was installed. Not sure what to do next to fix the issue!