Coolant temperature gauge
Examination
If the coolant temperature gauge does not work, check the condition of the fuses.
If the coolant temperature gauge indicates engine overheating immediately after starting the engine, remove the electrical connector from the engine temperature gauge. The sensor is located on the bottom of the thermostat housing on HCS and Endura-E engines, on the thermostat housing on CVH and PTE engines, and on the front of the thermostat housing on Zetec and Zetec-E engines. If the temperature gauge needle drops to 0, replace the engine temperature gauge sensor. If the temperature gauge needle indicates engine overheating, it is possible that the wire to the temperature gauge is shorted to ground or the engine temperature gauge itself is faulty.
If the engine temperature gauge does not show the temperature after the engine warms up and the fuses are in normal condition, then disconnect the connector from the engine temperature sensor and. using an additional wire, short the sensor contacts to ground. Turn on the ignition without starting the engine. If the engine temperature gauge shows engine overheating, then the engine temperature sensor must be replaced.
Removal
Remove the air filter or ventilation hoses.
Drain the coolant.
On Zetec and Zetec-E engines, disconnect the expansion tank coolant hose and the radiator upper tank hose from the thermostat housing.
Disconnect the electrical connector from the engine temperature sensor.
Unscrew the sensor and remove it.
Installation
Clean the sensor mounting hole. Then apply a layer of sealant to the sensor threads and screw the sensor into place. Connect the electrical connector to the sensor.
Connect the cooling system hoses and install all previously removed components. Add coolant to the cooling system. Start the engine and check the cooling system for leaks.
Coolant temperature sensor
Examination
Remove the negative terminal from the battery.
The coolant temperature sensor is located under the exhaust manifold on HCS and Endura-E engines or in the center of the exhaust manifold on CVH and PTE engines or on the top of the thermostat housing on Zetec and Zetec-E engines.
Disconnect the electrical connector from the sensor.
Using an ohmmeter, measure the resistance between the sensor contacts. Depending on the sensor temperature, the measured resistance may vary, but should be within the limits specified in the technical specifications. When the sensor cools or heats up, its resistance should change.
Removal
Disconnect the negative battery terminal.
Remove the air filter housing and engine air supply system components to access the sensor.
Drain the coolant from the cooling system.
Disconnect the electrical connector from the sensor.
Unscrew the sensor and remove it.
Installation
Clean the sensor mounting hole. Apply a thin layer of sealant to the sensor threads, screw the sensor into place and connect the electrical connector to it.
Install the air filter housing and crankcase ventilation system components.
Radiator Fan Thermal Switch
Removal
Remove the negative terminal from the battery.
Drain the coolant from the cooling system.
Remove the electrical connector from the radiator fan temperature sensor, then unscrew the sensor from the thermostat housing or the upper radiator tank hose.
Installation
Installation is performed in the reverse order of removal. Fill the cooling system with coolant and connect the negative battery terminal.