A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
GMC Yukon Denali Check Engine Light Due to Gas Cap Issue
GMC Yukon Denali Problem
Average Mileage: 139,328 mi (118,657 mi - 160,000 mi)
replaced, gas cap and removed negative battery term for2 min. light went out.
Visitor, 2007 GMC Yukon Denali, 118,657 mi
Check gas cap light came on, tighten gas cap. A day later the light came on again. We replaced the cap. A week lated it happen again.
Visitor, 2007 GMC Yukon Denali
Got a diagnosis with a code using the code machine...the code could have been a couple things related to gas, but it was determined that it was just that the gas cap was too loose ....just replace the cap.