The engine coolant temperature sensor measures coolant temperature. The engine temperature sensor is a Negative Temperature Coefficient (NTC) type sensor, as the temperature increases the resistance decreases.
Coolant passes through the cylinder and by the sensor probe, varying a resistance reading which is relayed to the ECU. This signal is processed by the ECU and compared to its programming for determining the fuel and ignition requirements during operation. The ECU also uses this signal to determine when to activate the fan during operation.
ECT Sensor Test
To quickly rule out other components and wiring related to the ECT, disconnect the harness from the ECT sensor and start the engine. After a few seconds, the fan should turn on and the “Over Temp” indicator should display on the instrument cluster. This indicates all other components are working properly.
ECT Sensor Resistance Readings
Temperature °F (°C)
32 °F (0 °C)
68 °F (20 °C)
176 °F (80 °C)
212 °F (100 °C)
12 sportsman 850XP EPS : So far its stock