Illumination of the Check Engine Light can be caused by a loose or worn gas cap.Google+
Car Problem Reports
Saturn SL2 Check Engine Light Due to Gas Cap Issue
Saturn SL2 Problem
Average Mileage: 98,860 mi (29,157 mi - 150,000 mi)
Visitor, 2001 Saturn SL2, 108,000 mi
check engine randomly comes on and goes off since September, now I am having problems getting the gas cap off. Code that comes up is cylinder 1 misfire.
Visitor, 2000 Saturn SL2
I've had this problem for more than a year, and have had the gas cap changed, and it still happens off and on.
Visitor, 2002 Saturn SL2
If gas cap isn't screwed on tightly, Check Engine light will come on after a few times. After correcting problem, it takes several more good trips (far enough to heat engine) before it goes out.
New Gas cap
Visitor, 2000 Saturn SL2, 105,006 mi
I've had this problem twice since I've owned this car (6 months). The first time it just went away on its own after reading a "small evap leak" check engine light code. Light came on again just 3 days ago... hoping it will just go away on its own again.