A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Chevrolet Cobalt Check Engine Light Due to Gas Cap Issue
Chevrolet Cobalt Problem
Average Mileage: 82,107 mi (43,000 mi - 120,000 mi)
Visitor, 2006 Chevrolet Cobalt, 84,000 mi
check engine light is on.Digital display read "check gas cap" once and the check engine light wont go off.After I pump gas it takes 5 mins for my car to start. Found out that this was because its taking longer for the pressure to build back up in the gas tank.
check engine light comes on after gas cap indicator comes on and stays on
Visitor, 2005 Chevrolet Cobalt, 100,000 mi
Same issue as everyone else... I have had so many issues i would never buy a Colbolt again
Visitor, 2006 Chevrolet Cobalt, 85,000 mi
check engine light on...no problems...car run great
Visitor, 2008 Chevrolet Cobalt, 43,000 mi
Engine Light came on and Check Gas Cap message appears
Visitor, 2006 Chevrolet Cobalt, 117,000 mi
Check engine light for loose gas cap. Turned out to be a leaking and cracked fuel pressuriztion device near the gas tank.