Engine Coolant Temperature Sensor Assembly for Subaru ️
This sensor tells the ECU exactly how hot the engine is. With precise temperature data, the computer sets fuel mix, ignition timing, idle speed, and radiator fan operation. The result is smooth cold starts, stable idle, strong performance, and better fuel economy with lower emissions.
How it works ⚙️
Inside is a sealed NTC thermistor. As coolant warms, its resistance drops. The ECU reads this change through a 5V reference and ground, converts it to temperature, then adjusts injectors, spark, and fan relays. A tight brass body and OE-style connector ensure clean signals and long life.
What happens if it fails ❗
Symptoms include hard cold starts, rough idle, poor mileage, black smoke or fuel smell, weak throttle response, fan stuck ON/OFF, and check engine light (temp circuit codes). Prolonged faults can cause overheating, warped head, or catalytic converter damage. Intermittent readings may also trigger transmission harshness.
Install tips
Work on a cool engine. Swap quickly to minimize coolant loss. Use a fresh sealing washer or approved thread seal (if specified), tighten to spec—snug, not brute force. Reconnect the plug clean and dry, refill/bleed coolant, and clear codes. Verify fan cycling and live temp data.
Compatibility
- Impreza
- Forester
- Sambar
- Legacy
