3922003HA0 Hyundai / KIA SENSOR ASSY-WATER TEMPERATURE, Price: 9.73$, Weight: 0.008kg

Engine Coolant Temperature Sensor (Water Temp)

This sensor is a key input for the ECU to manage fuel mixture, ignition timing, radiator fan operation, and cold-start strategy ?️. It’s needed because modern engines must know the exact coolant temperature to run efficiently, reduce emissions, and prevent overheating.

How It Works

Inside the sensor is a thermistor that changes resistance as coolant temperature changes. The ECU reads this signal as a temperature value, then adjusts engine parameters in real time. When the engine is cold, the ECU enriches fuel and raises idle; when hot, it leans the mixture and can command the cooling fan sooner.

What Happens If It Fails

A faulty unit can send a false “cold” or “hot” reading. That may cause hard starting, rough idle, poor fuel economy, black smoke, fan running nonstop, overheating risk, or a check engine light. Long-term driving with wrong temperature data can stress the catalyst and lead to engine damage ?.

Compatibility

• 6 Wagon