This could be the result of a number of things. I would recommend taking the vehicle into your local dealership to be diagnosed. They should be able to assist you further and have a plan for addressing the issue. I can also look into this issue further. In order to do so, I will need some more specific information from you. If you could please send me your full name, address, phone number, the VIN for the vehicle, current mileage, and dealer name via private message, I will be able to take further steps. Thank you again and I look forward to hearing from you.
Tricia, GM Customer Service.