One problem related to timing tensioner has been reported for the 2012 Buick Regal. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Buick Regal based on all problems reported for the 2012 Regal.
Vehichle purchased in October 2017 with 35k miles. Has always had a vibrating noise while sitting and idling. It will get worse after the car is driven/heated and then idled. Brakes have always had a very loud screaching noise. Tail lights stopped working. Bulbs were changed and they have worked since. However, the headlights stopped working. Bulbs were changed with no satisfaction. Fuses were changed and blew every time. Took vehicle to mechanic shop - diagnosed. Brakes are ok. Per his words, just cheap setup. (this was how I purchased the car, I've never replaced the brakes since purchasing), the tensioner pulley was causing the vibration. Pulley and belt (stretched) were changed, headlamp assembly's (both) needed to be changed as they were not getting power ($1600. 00 each!!! the ballasts were bad), also had my high pressure line for a/c changed as that quit working as well.