Pontiac Repair: temp gauge reads hot, head gasket leak, pontiac sunfire

Question
Hi Todd, I have a 2001 Pontiac Sunfire 4cyl. 2.2 engine.  The temp gauge is pinned on hot and check gauges light comes on.  I had it to the mechanic and it is not the head gasket.  I have replaced the thermostat, the water pump, and even had a new radiator put it and it still does the same thing.  What else is left?  should I look at the coolant sensor and maybe the catalytic converter?  This is driving me crazy!  The car runs fantastic even when it is pinned on hot.   Thank You

Answer
Hi Judy:

Is the car indded running hot? Or is just the gauge off? Lets start there. If it indeed is running hot I'd take a look at the electric cooling fan make sure that is working properly. If so then I would look at posssably a air flow issue between the radiator and the condenser if the car is equipped with A/C? if that is okay then I would look long and hard at a possable head gasket issue. These engines are noted for that. There is a chemical that can be put into the antifreeze and if ther is exhaust gases in the coolant "from a head gasket leak" the chemical will chnage colors and let you know if there is indeed a leak. Good luck :)