The engine coolant temperature sensor (also known as the coolant temperature sending unit) is a small sensor screwed into the thermostat housing. The sensor measures the temperature of the coolant and relays that information to the temperature gauge on the dash. It is also responsible for illuminating the warning light if the coolant reaches a temperature where the engine could be damaged. If the temperature gauge in the dash of your Chevrolet Cavalier no longer works, you may have to replace this sensor.
Disconnect the ground cable from the negative battery terminal. Loosen the retaining bolt using a wrench, then pull the clamp off the terminal.
Locate the petcock valve on the right side of the radiator, and place a waste oil collection pan underneath it.
Open the valve by turning it counterclockwise with needlenose pliers.
Close the valve by turning it clockwise (after all the coolant has drained out) using needlenose pliers.
Locate the thermostat housing. It will be located between the upper radiator hose and the engine.
Detach the electrical connector from the coolant temperature sending unit by pulling it off. The sending unit will be screwed into the thermostat housing.
Unscrew the sending unit from the thermostat using a wrench.
Coat the threads of the new coolant temperature sending unit with a thin coat of RTV silicone sealant.
Screw the sending unit into the thermostat. Tighten with a wrench.
Fill the radiator with a 50/50 mix of antifreeze and water.
Reconnect the ground cable to the negative battery terminal. Slide the clamp over the terminal. Tighten the retaining bolt using a wrench.
Run the engine and visually inspect for leaks.
