cleo299

08 M6 Vert - I am pretty sure the coolant temperature sensor failed. Coolant temperature gauge is pegged low. Coolant level is full. Hoses feel normal. Oil temperature is normal. DIC displays high engine temperature warning, turn off A/C.

Is there a description on how to replace the coolant temperature sensor on this forum? (I can't find it).

cranky

most likely the thermostat has failed or the fan is running too high. you need to take a hand held lazer temp tool and check the upper hose after driving it for awhile and see if it is running below 195 degrees F. if so, check and see if the fan is running fairly high all the time. if the fan speed is ok, the thermostat is staying open all the time. this will also cost you in fuel milage too. the computer will not go into closed loop and deliver more fuel to the engine. if you replace the thermostat yourself, be advised the cooling system will need the air bled out of it when you refill the system. get a service manual to see how to properly bleed it. otherwise, you will have overheating issues. good luck

Ahmer

And I too am having a similar problem. My car never overheats but has the coolant temp fluctuating all over