Check Engine Light Due to Gas Cap Issue on Buick Century

Problem Description and Possible Solution

Illumination of the Check Engine Light can be caused by a loose or worn gas cap.

Problem Data
RepairPal Verified
Average mileage: 94,187 (28,000–169,000)
11 model years affected: 1994, 1996, 1997, 1998, more1999, 2000, 2001, 2002, 2003, 2004, 2005
48 people reported this problem
Viewing 1 - 18 of 18 comments
still not fixed have had the problem for years. Have had it into the shop they said gas cap replaced that it worked for about a week then back to the same problem everything has been checked they find no reason for it
2003 Buick Century code P0442. Evap system (small leak). Bought replacement fuel cap from GM (I read that it must be from GM). No "service engine light" after 50 miles.
When I bought my car, I bought a locking gas cap. When I took my car to get it fixed, the guy told me to try the old gas cap and the check engine light went off.
check engine light came on. Mechanic checked code, cleared it and suggested we tighten gas cap to at least three "clicks". Three months later problem has not returned
NEVER overfill your gas tank. When filling up and the gas hose clicks off at the pump DO NOT fill to max. Also Make sure the gas cap is tight after filling so as not to create a vaccum. Common sense fixes this problem.
I had to have the gas cap replaced because the light kept coming on and once the cap was changed no more problems.
check engine light came on and stayed on code said vacume leak I replaced gas cap with new one and cleared code and light never came on again.
Was in Florida and the light came on and when I got gas the cap was lose, tightened it up drove for a 1000 miles ant went off. Later same problem tightened it and light went off in a few miles.