A Loose or worn gas cap may cause Check Engine Light to illuminate.Google+
Car Problem Reports
Buick LaCrosse Check Engine Light Due to Gas Cap Issue
Buick LaCrosse Problem
Average Mileage: 60,024 mi (10,200 mi - 110,000 mi)
Check engine light stayed on. Remote diagnostic (Onstar)indicated that problem was with the gas cap. Took car to dealer, told them and they replaced the cap. Problem resolved.
Visitor, 2008 Buick LaCrosse, 22,098 mi
gas cap light cap looks ok then engine check light guess I should of bought a donkey
Visitor, 2005 Buick LaCrosse, 37,000 mi
Check engine light
Leak in pressurized system
Gas inlet defective
Replaced $77 at dealer
Visitor, 2008 Buick LaCrosse, 80,000 mi
Check gas cap light keeps coming on intermittently and now check engine light on. Replaced gas cap
and okay for awhile. Both engine light and check gas cap light went off. Now, back on again.
First check gas cap (which I did) and now engine light.
Visitor, 2006 Buick LaCrosse, 52,000 mi
I have selected "me too" to 3 other common problems with the Lacrosse. I contacted buick for assistance on repairs and they said Garber Buick in Saginaw Michigan would only agree to $50 assistance on a $443 repair bill. How sad! But they had no problem taking bail out assistance from my tax paying money!!!!!!!!!!!!
We had this issue too. Mechanic found the problem.
Visitor, 2012 Buick LaCrosse, 27,213 mi
Check engine light on first time at 18,000 miles this was due to a bad wire from gas tank to sensor fixed light went out at 27,000 miles it lit up again this time they had to drop the gas tank and replace the sensor.Will see if this comes back.
Visitor, 2008 Buick LaCrosse, 110,000 mi
Check engine light came on at approx. 35,000 miles. Got gas cap replaced. Didn't have any more problems until approx. 110,000 miles. Have retightened the cap several times. Light went out the first few times. Now stays on. Will have to replace the cap again.
Visitor, 2008 Buick LaCrosse, 79,000 mi
Intermittently check engine light and check gas cap message appear, I have tightened gas cap again and again.
But this time the check engine light isn't going away. About 5th time now.
As another post stated...I will try auto zone and see whatever code is given when the scan the system.
Visitor, 2010 Buick LaCrosse, 73,000 mi
Check engine light is on and the dash reads "Tighten Gas Cap" . I've tightened the gas cap several times I'm taking the car to the dealer tomorrow.