Illumination of the Check Engine Light can be caused by a loose or worn gas cap.Google+
Car Problem Reports
Buick Terraza Check Engine Light Due to Gas Cap Issue
Buick Terraza Problem
Average Mileage: 102,271 mi (75,000 mi - 157,000 mi)
The check engine light stays on and periodically the indicator warning flashes saying check gas cap. I have replaced the gas cap, but nothing changed.
Visitor, 2005 Buick Terraza, 130,000 mi
The check engine light came up due to gas cap issue. does anybody know how to correct this issue?
Visitor, 2006 Buick Terraza, 96,131 mi
gas cap light comes on and the next day chech engine light comes on; ask dealer about this and he stated there could 5 0r 6 things that cause this--to check this $90.00 not counting repairs.
Visitor, 2005 Buick Terraza, 75,000 mi
Check engine light came on. Replaced gas cap and light went off.
Same issue, engine light is on. It states to "check gas cap." I replaced the gas cap twice and had the dealer to reset the light. Came back on the next day.
Visitor, 2005 Buick Terraza, 85,000 mi
Check engine light illuminates periodically but then corrects itself.