Anyone able to tell me if this issue is a thermostat or the sensor? My 02 GP 3.1l temp guage started fluctuating a lot and heat would work then not work...after 2 days now the heat is completely gone amd guage is still fluctuating? Any ideas as im stuck fixing this myself. [emoji19]

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Have you checked the coolant level? Not sure if you have the plastic waterpump elbows on that one.i did and they cracked and leaked.

It's not that simple to answer without being there. Many things and multiple things can be involved. That said, with it being a 02 I’ll assume the antifreeze has been changed seldom. If it's never been flushed and if most or all of its life there's been Dex Cool in the system you most likely have major blockage. If that's the case it will require a complete redo of the coolant system. Water pump, lines, heater core and radiator. What you described makes me lean towards that. So you will need to verify that condition before you start down that road.