Mercury F5AZ-12A648-A Sensor - Engine Temperature, ECT

The coolant should be checked to ensure it is of the proper type and mixture.

In later 7.3L and 6.4L models, the ECT sensor is located in the engine front cover.

If the gauge reads full HOT when jumped but not when the connector is plugged in with a hot engine, the coolant temperature sending unit is faulty.

To test the temperature sender, it should read in the cold range when the engine is cold. Disconnect the electrical connector from the sender and attach a jumper wire between the two pins of the connector. With the key ON, the gauge should swing to full hot. If it doesn't, there may be a problem in the circuit from the sender to the instrument panel.

Drain coolant from the radiator to approximately four inches below the upper radiator hose.

For 2001 and later 2.3L models, disconnect the battery, expose the electrical connector, unscrew, and replace the Cylinder Head Temperature (CHT) sensor.

Before replacing the sending unit, allow the cooling system to completely cool down and open the cooling system pressure cap to relieve any pressure in the cooling system. Install the cap to minimize coolant loss.

On V6 engines, the sending unit for the gauge is located on the front lower part of the intake manifold, near the thermostat housing.

The power steering pressure switch affects idle quality, and problems may set Code 52. You should check for open or closed circuits affecting engine timing.

To replace the coolant temperature sending unit, the electrical connector should be disconnected, and then the sensor can be unscrewed from the engine and the replacement installed.

When replacing the sending unit, it is important to prepare the new unit by wrapping its threads with Teflon tape or applying sealer.

3F1Z12A648A SHOWS AS THE CORRECT PART NUMBER FOR THE VEHICLE