Illumination of the Check Engine Light can be caused by a loose or worn gas cap.Google+
Car Problem Reports
Chevrolet Suburban 2500 Check Engine Light Due to Gas Cap Issue
Chevrolet Suburban 2500 Problem
On vacation in Florida, 1200 miles from home. Check engine light illuminates and I was lucky enough to be in an area where there was a dealer who stayed open later in the evening. The gentleman at the entry gate ran the code and it came back as a gas cap failure. Purchased and installed new cap and dealer reset computer. This seemed to be a cheap and easy fix. Approximately 800 miles into my return trip I recieved the same code via On-Star. I have replaced the cap 3 times with OEM equipment. Problem still exists. No problems with performance but I live in an area that requires emission inspections and now the code returns before the 100 mile requirement for the state regualated equipment will allow my inspection.