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
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!