I read a thread about the temperature sensor in the water pump and if it isn't working correctly it could cause all kinds of performance issues. I hooked up the lap top and started the car. It was 39 degrees F outside and when i started the car the reading said 69 degrees F. It started in seconds to rise and was climbing to the point that it hit the 160 that the thermostat is at. I don't know if there is a mininum the reading should start at but it sounds like it might be bad. I used Freescan to get the reading.

 

had the3 car sat overnight? or had it been running already?

 

Sat for over 12 hours so it was good and cold.

 

On a cold overnight soak, compare it's reading to that of the IAT. If it's more then about 3* off, replace it. IAT is easy to confirm just by comparing it to the ambient temp.

 

I bought one through the GM dealer for $13. Not wondering if it could have been the sensor made it worth the price alone.