Help With Temperature Gauge issue!

**gcschi22** · 12-01-2011

Hi, Ive recently replaced just about everything for my cooling system on my grand prix. (New radiator, hoses, heater hose fittings, water pump, thermostat, coolant temp sensor). . The car has 185k and the cooling system was due for a overhaul. After replacing everything on the coolant system, the temp gauge seems to be giving an incorrect reading in the car.. it will fluctuate from about 220 to about 245 degrees in the car (which is pretty damn close to overheating according to the temp gauge), and i laser temped the thermostat housing, the block, heater hose fittings, and the readings never exceeded 215.. What would cause the gauge to read high like that? faulty coolant temp sensor? i have no service engine lights, low coolant lights or anything.. everything seems to be in good working order besides the gauge. Any help would be greatly appreciated. Thanks!

* also i bled the system thoroughly using a bleeder funnel and opening the bleeder valve until a steady stream of coolant came out.

**Kejross** · 12-01-2011

I would get a scanner and read what the computer is seeing from the temp sensor instead of going by the crappy gauge on the dash. If the temp sensor is showing about the same thing your seeing with the gauge then I would assume that either the temp sensor was bad or the car is actually getting hot. And thanks for letting us know you bled it cause that woulda been my first suggestion...

**gcschi22** · 12-01-2011

Thanks For your help, i will scan the vehicle tonight and see how it goes.

**BillBoost37** · 12-01-2011

Keep in mind..there are two sensors built into that one. One feeds the pcm and the other feeds the dash. If you see a difference, it's likely the sensor. If you see them alike...it could be a stubborn air bubble and or the wiring to the sensor.

**gcschi22** · 12-01-2011

Thanks for your replies. I scanned the car today and the ECT reads on the scanner normal around 205-210 degrees while my gauge reads near 240. I do see the connector that plugs into the coolant temp sensor plugs into the harness near the fuel pressure regulator.. maybe its bad.. but i bought another coolant temp sensor just in case.. im thinking its faulty. It should be good to drive as long as the pcm is reading the temperature right, correct?