Mercury F65Z-6G004-AB Sensor Assembly

The cylinder head temperature sensor, a key part of the Fail Safe Cooling system, adjusts its voltage output based on temperature changes. As the sensor temperature drops, resistance values and voltage increase. If the cylinder head temperature surpasses 265 degrees F, the PCM deactivates four (V8) or five (V10) fuel injectors, using the unfueled cylinders as cooling air pumps. At 330 degrees F, all fuel injectors are disabled. To replace the sensor, the intake manifold must be removed, the electrical connector unplugged, and the sensor unscrewed and replaced.

The CHT sensor is situated on the 3.5 L and 4.2L V6 engine left cylinder head rear end; it is better accessed underneath due to the close proximity. First, remove the cable from the negative battery terminal and proceed to lifting the front part of the vehicle using jack stands. To remove the old CHT sensor, you have to unplug the electrical connector from the CHT sensor, then unscrew it with the help of a wrench or socket and then remove it. Installation is the complete opposite of removal where the sensor is tight to the recommended torque. For 4.6L and 5.4L V8 models, CHT sensor is mounted on the inner side of the right cylinder head, so one has to remove the intake manifold to get at the sensor. Disconnect the negative battery terminal, and for the 2-valve 4.6L engines only, also remove the alternator and intake manifold, relieve the fuel system pressure. Pulling the tab, there are actually two connectors, unplug the electrical connector, and then, using a wrench or deep socket, loosen the screws and take out the CHT sensor. Reinstallation is done in an opposite manner and always with the right amount of torque. In 3.7L V6, 5.0 L and 6.2L V8 models, CHT sensor is fitted either under the lower intake manifold gasket, lower intake manifold or the intake manifold. Rub the earth lead off the battery, take out the intake manifold, and remove the electrical connector of the CHT sensor. The removal of the sensor requires a wrench or deep socket in addition to the correct tightness on the reinstallation.

CHT sensor is used on all engines excluding the 4.0L V6 engines of some models. For 3.7L V6 engines, the sensor is located, and needs access near the front of the engine beneath the intake manifold. For 4.6L V8, it is located on the right side on the cylinder head or under the intake manifold where the sensor has to be unbolted to get at. for 5.0 L V8 engines, such a sensor is installed at the back of one of the right cylinders, and it is pointed upwards toward the opposite cylinder. It is possible to start by removing an end of the cable and then separating it from the negative terminal of the battery. For 3.7L V6 or 4.6L V8 engines, if necessary, remove the intake manifold. Following this, remove the electrical connection to the CHT sensor; to have the sensor removed from the head, the electrical connection has to be disconnected then the CHT sensor unscrewed. For the previous year models, the manufacturer warned that if the CHT sensor is removed, another new one should be fitted to it. Lastly, disconnect the CHT sensor by unscrewing it and then, the installation should be done in the reverse manner with the right tightening of the sensor to the right torque.