Illumination of the Check Engine Light can be caused by a loose or worn gas cap.Google+
Car Problem Reports
Saturn SL1 Check Engine Light Due to Gas Cap Issue
Saturn SL1 Problem
Average Mileage: 187,666 mi (149,000 mi - 218,000 mi)
Visitor, 1998 Saturn SL1, 149,000 mi
Check engine light came on, required only a gas cap replacement.
This isn't unusual for a car that's 12 years old. I just had to replace my Saturn's gas cap because after 12 years, its seal had become worn out and caused the check-engine light to come on.