Kia Niro: Engine Control System / Engine Coolant Temperature Sensor (ECTS) Description and operation

Located in the engine coolant passage of the cylinder head, Engine Coolant Temperature Sensor (ECTS) detects the engine coolant temperature. The ECTS uses a thermistor with resistance in proportion to the temperature.

The electrical resistance of the ECTS decreases as the temperature increases, and increases as the temperature decreases. The reference +5V is supplied to the ECTS via a resistor in the ECM. That is, the resistor in the ECM and the thermistor in the ECTS are connected in series. When the resistance value of the thermistor in the ECTS changes according to the engine coolant temperature, the output voltage also changes.

During cold engine operation, the ECM increases the frequency of fuel injection and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve drivability.