Hyundai Ioniq (AE): Engine Control System / Engine Coolant Temperature Sensor (ECTS). Description and operation
Engine Coolant Temperature Sensor (ECTS) is located in the engine coolant passage of the cylinder head for detecting the engine coolant temperature. The ECTS uses a thermistor that changes resistance with 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 fuel injection duration and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve drivability.

Inspection1.Turn the ignition switch OFF.2.Disconnect the IATS connector.3.Measure resistance between the IATS terminals 3 and 4.4.Check that the resistance is within the specification.
Specification
Temperature
Resistance (kΩ)
°C
°F
-40-4048.
Other information:
Replacement1.Disconnect the negative (-) battery terminal. 2.Remove the heater and blower assembly.(Refer to Heater - "Heater Unit") 3.Loosen the mounting screws and remove the driver's temperature control actuator (A).4.Remove the heater core cover (A) after loosening the mounting screws.
DescriptionRear view monitor (RVM) will activate when the backup light is ON with the ignition switch ON and the shift lever in the R position.This system is a supplemental system that shows behind the vehicle through the AV monitor while backing-up.
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This system is a supplementary function only.