A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Cadillac CTS-V Check Engine Light Due to Gas Cap Issue
Cadillac CTS-V Problem
Average Mileage: 67,093 mi (55,170 mi - 88,109 mi)
Visitor, 2007 Cadillac CTS-V, 55,170 mi
My Check engine light comes on after I fill up with Gas. that has happened the last 3 times I filled up.
My computer notified me that I should "check gas cap" and now my "check engine light" is on.