A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Chevrolet Aveo5 Check Engine Light Due to Gas Cap Issue
Chevrolet Aveo5 Problem
Average Mileage: 26,706 mi (12,413 mi - 41,000 mi)
Visitor, 2007 Chevrolet Aveo5, 41,000 mi
check engine light came on and i remember reading about this somewhere .checked gas cap and it wasn't tight.shut the car off and re-tightened.started car,cleared the code and the light didn't come on again.