Check Engine Light Due to Gas Cap Issue on Pontiac Sunfire

Problem Description and Possible Solution

Illumination of the Check Engine Light can be caused by a loose or worn gas cap.

Problem Data
RepairPal Verified
Average mileage: 131,237 (30,000–332,345)
10 model years affected: 1996, 1997, 1998, 1999, more2000, 2001, 2002, 2003, 2004, 2005
32 people reported this problem
Viewing 1 - 9 of 9 problem details
check engine light on but says evap code
got new cap
Purchased new gas cap.
check engine light comes on p0440 code replaced gas cap light will not go out
check engine light comes on, cause, fuel cap
check engine light on and replaced cap waiting to see the light go off hopefully soon
Engine light came on. Turned out the cause was the gas cap not being securely tightened. You have to hear clicks to be sure it's tight. My cap was very dirty. Cleaned it and it was fine but soon replaced it.
I can always tell when someone other than myself has messed with the gas tank lid....either its coiled up all wrong or i ge the check engine light...I then make sure during my next stop to undo the cap and retighten it, making sure it clicks at least 2-3 times. Usually, the check engine light will then go off after a couple of restars after the cap has been retightened.
My check engine light was on so i went to mechanic and it was diagnosed as it being the gas cap. replaced gas cap-problem solved! ;)