Illumination of the Check Engine Light can be caused by a loose or worn gas cap.Google+
Car Problem Reports
Saturn L200 Check Engine Light Due to Gas Cap Issue
Saturn L200 Problem
Average Mileage: 101,750 mi (68,000 mi - 156,000 mi)
Visitor, 2002 Saturn L200, 115,000 mi
The "check engine soon" light came on after I had the fuel pump and lines replaced due to rust and gas leakage. After the replacement, the light came on. My mechanic dropped the gas tank again to check for a problem, but was unable to pinpoint issue. No problem with mileage or the car running. Due to the light, VA failed the car for the emissions test. Reset the light, and it hasn't come back on yet.
Visitor, 2001 Saturn L200, 156,000 mi
Loose gas cap caused check engine light to come on.