i have had this car since 1989 100% stock replaced electric fan couple years back. radiator sides started to leak so i ordered and installed a new radiator. using a infrared thermometer aimed at the thermostat housing and different areas of the engine and radiator the cooling fan comes on at 160 degrees. and back off at about 155 degrees. the temp gauge goes to the first quarter mark. everything is 100% stock on this car. cooling system was clean as a whistle when the old radiator gave out. it has 170,000 trouble free miles on it. what gives. steve

 

Bad Coolant Temp Sensor (in intake by thermostat, two wires yellow and black) or bad fan switch (in pass side head, single wire, mushroom connector - NOT to be confused with the knock sensor in pass side BLOCK that has same connector type) or both maybe? Is car running rich, gas mileage bad? I'd assume it might be since car never really "warms up", and the CTS would be giving false info to the ECM about engine temps maybe.

{I'm guessing here, I'm certainly no expert}

 

car runs great and decent gas mileage. steve

 

your car is plenty warm at 160degs. esp with iron heads.
coolant temp has nothing 2 do with 02sensor temp.
only reason new cars run 210-220 is emisions (sp) im very tired)
drive it and enjoy.