Have a 06 cts 2.8l v6 with the check engine light that came on. I took it in and the place told me that the thermostat is sticking and it needs to be replaced and they want four hundred to replace it and there is four hours of labor involved because its on the back of the motor and very hard to reach.Then they tell me that the car is ruining at 192 degrees and the computer is only reading it around 140 degrees and that is what caused the check engine light to come on. the car seems to be fine and not over heating. Thinking its a sensor and replacing that and the thermostat myself.