A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Chevrolet Express 3500 Check Engine Light Due to Gas Cap Issue
Chevrolet Express 3500 Problem
Exhaust & Emissions Affected: Gasoline
Visitor, 2010 Chevrolet Express 3500, 110,000 mi
check engine light came in driving in IL IN and KY. Went back out when I got back to TX where it was alot warmer. Happened twice on diffrent trips into a colder climate. Turned out to be a bad gas cap...