Oldsmobile/Buick Repair: 2001 Shilouette thermostat problem, obd ii, shilouette

Question
Hello,  about 6 weeks ago the temp gage on the panel was peaked out, and the last few days the gage does not move from cold.  I did an OBD II test and it indicated PO128; something with the thermostat.  Is there a way I can test the sensor before I attempt to replace the thermostat (it's in a difficult spot)?

Answer
Hi
I have a vehicle with the IDENTICAL problem in my stall right now.
Is your cooling fans on all the time?
If so, it is either the PCM )Computer) or the BCM Body computer. Both control the fan operation
Mine ended up being the PCM, it had the fans commanded on all the time.
Please follow post back if needed.
Hope this helps.
Pawl