My 2001 monte was operating fine at correct temperature on commute to work; then like switching a switch, the temperature gauge goes down to the coldest it can go. The fans near the radiator also stayed on for about 10 minutes after shutting the car off, as if my motor was hot, but it was not. I could open the radiator cap and the antifreeze was full in the radiator but only warm to the touch. The heater was still blowing out fairly hot air as well. Any ideas?

 

Temperature sensor went bad, car doesn't know how hot the engine truly is and enters a fail-safe mode.

 

Thanks for the reply. Is the temperature sensor located under the thermostat? And if so, is it part of the thermostat? If not, should I replace thermostat at same time?

 

It is located below the thermostat housing yes, you will lose coolant so you'll need a bottle of 50/50 to replace what you lose.

A good time to just do a quick coolant flush + thermostat change IMO. Especially if you can't remember the last time you did one.

 

I had this happen on my son's 2001 Impala it turned out to be the thermostat,after I changed the thermostat it went back normal..

 

im going through a similar issue right onw with my 01 SS, I have replaced the sensor and gauge, its seems to be a faulty temp harness.