Pontiac Repair: Normal Temp Guage Reading, coolant temp, pontiac grand prix

Question
I own a 2000 Pontiac Grand Prix GT(3800 Series II V6 engine). What
is the normal temperature guage reading on this car? It now reads
at 210 or higher but before replacing the thermostat & coolant temp sensor, it hung right at the 170 or so degree mark under normal driving conditions(since 2000). Was my original thermostat defective all those years or do i still have a problem("service engine soon" light caused the repair). Any assistance would really be appreciated!

David

Answer
Hi David:

The temp gauge on the dsah is onl;y an indicator it's not an excat reading it's close but not exact. The factory thermostat's are usually 195 degrees. the operating temp range could be as high as say 225 degrees and it depends on ambient temp and humidity along with the a/c being on in the car will change the temp as well. the cooling fan(s) on these care usually will not come on untill the temp is over 220 degrees with out the a/c being on.. if the temp was low all the time then yes it can cause cause a service engine soon lamp on with a code p0128 which is a low operating temp code due to the thermostat opening up too soon. good luck :)