A Loose or worn gas cap may cause Check Engine Light to illuminate.
Car Problem Reports
Buick LaCrosse Check Engine Light Due to Gas Cap Issue
Buick LaCrosse Problem
Model Year Affected: 2005
Average Mileage: 89,333 mi (60,000 mi - 128,000 mi)
Visitor, 2005 Buick LaCrosse, 60,000 mi
Check engine light csame on, pulled trouble code it was stating gas cap problem replaced cap. turned out to be a bad sensor in the gas tank.
Visitor, 2005 Buick LaCrosse, 80,000 mi
In shop now for this and a power steering issue (I don't have details yet)
light is coming on occasionally even though cap is tight.