Check Engine Light Due to Gas Cap Issue on Buick LaCrosse

Problem Description and Possible Solution

A Loose or worn gas cap may cause Check Engine Light to illuminate.

Problem Data
RepairPal Verified
Average mileage: 70,474 (10,200–167,000)
8 model years affected: 2005, 2006, 2007, 2008, more2009, 2010, 2012, 2014
52 people reported this problem
Viewing 1 - 20 of 28 comments
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.
We had this issue too. Mechanic found the problem.
The check engine light come on
Check engine lights comes on. I have to tighten the gas cap and it goes off. But this happens every time I fill the tank.
gas cap light cap looks ok then engine check light guess I should of bought a donkey
Check engine light
Leak in pressurized system
Gas inlet defective
Replaced $77 at dealer
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.
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!!!!!!!!!!!!
I had the same problem with the check engine light always coming on. I would remove and replace the cap quite often and the light would eventually go off. Finally that stopped working so I went ahead and bought a new cap. Replaced the cap, filled the tank with gas, added some of that adatech additive for good measure, and the light went out the next day. It was worth a try because the Buick dealer would charge $130 for a diagnostic on the check engine light. Gas cap was $16 online. Another blog site mentioned putting vasoline around the seal area of the cap. Might be worth a try before getting a new cap. If my new cap starts acting up, I'm going to try the vasoline thing. Makes sense....as it does appear to be related to the seal.
check gas cap would come on if you did not clear it then check engine light comes on
Bought new gas cap Check engine light still came back
Always low feul gas cap or chek gas cap
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.
loose gas cap
on occation right rear lock doesnt unlock
MY CHECK ENGINE LIGHT IS ON AND MY ONSTAR DIAGNOSTIC IS SAYING THAT IT HAS SOMETHING TO DO WITH THE EMISSION SYSTEM.
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.
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.
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.