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: 91,833 mi (45,000 mi - 150,000 mi)
check engine light came on and message appeared that the gas cap needed to be tightened. had diagnosised to determind gas cap was no longer sealing properly- replaced gas cap, but check engine light still on
Visitor, 2004 GMC Yukon Denali, 70,000 mi
Engine light due to gas cap
Visitor, 2004 GMC Yukon Denali, 150,000 mi
Gas cap sensor triggers check engine light. Despite replacing gas cap at the dealership the light goes back on.
Visitor, 2005 GMC Yukon Denali, 86,500 mi
Gas Cap Seal
Visitor, 2005 GMC Yukon Denali, 118,000 mi
wire that connects to rear window defogger has broken off
Visitor, 2006 GMC Yukon Denali, 80,320 mi
check engine light
Visitor, 2006 GMC Yukon Denali, 50,000 mi
Worn gas cap causes check engin light to come on. Only the $25 GM cap works to fix the problem.
Visitor, 2007 GMC Yukon Denali
"tighten fuel cap" persistent problem, replaced cap, replaced tank vent solenoid (that fixed the slow fuel fill problem). Cleared faults for about a month then get a periodic "tighten fuel cap" and check engine.
Visitor, 2004 GMC Yukon Denali, 97,000 mi
Engine light on.
Visitor, 2008 GMC Yukon Denali, 67,000 mi
My check engine light came on and i took it in to get it diagnosed. it was a gas cap leak. they replaced it with a factory gas cap. i had an aftermarket locking cap before.