'08 Grand Prix Sensor/computer issues
 

On Saturday my wife left with out daily driver '08 Grand Prix and returned 5 min. later saying that the info panel started beeping and giving warnings of "hot coolant" "A/C off to conserve power" "Traction control off" and other things. She came home immediately and told me about the problem.
I went out, started it and it started right up but the rpms surged a couple of times almost stalling once, then settled down to normal idle. I backed out of the drive and when I put it in drive it again beeped and the "hot coolant" message came on the info panel.
I pulled back into the garage, open the hood and checked the coolant recovery tank, couple of inches in bottom of tank. Top radiator hose was hot, figured it should be if coolant was circulating.
Took it back out for a test drive, it started right up, idled smoothly and there were no problems on the 5 mile trip I took.
My wife then took it to run her errands with no more issues.
I used it yesterday again with no issues.
Has anyone else had anything like this happen to them. I'd like to think it was some kind of one time only freaky thing but something inside my head tells me it will pop up again sometime and probably not so close to home..

Just an up-date. It did happen again and she was able to limp into a service shop. Turns out that a mouse had found its way under the plastic engine cover and chewed into the engine temp sensor wiring insulation. When the exposed wires would touch and short out it would send the message to the computer that it was running hot setting it into limp home mode.
New wiring and good to go.
I also found evidence of mice under the same cover on my 2000 Bonneville.

I removed the covers from my wifes 2008 Grand Prix and my 2004 Bonneville. have them hanging on the wall in my shop.