Engine Coolant Temperature Sensor Voltage Above Normal

The engine computer is seeing a coolant temperature sensor reading of over 250°F (121°C), which is way too high and suggests a sensor issue or overheating.

The ECM receives a signal from the coolant temperature sensor that is outside the expected range, particularly higher than 250°F (121°C).

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Check coolant level: Ensure it's between the minimum and maximum marks in the reservoir.
2. 22. Inspect wiring and connectors: Look for frays, corrosion, or loose connections at the coolant temperature sensor.
3. 33. Measure sensor resistance: Disconnect the sensor and measure resistance across the terminals; compare with expected values (should be around 5,000 ohms at 176°F).
4. 44. Check for overheating: Use an infrared thermometer to verify actual engine coolant temperature; ensure it matches what the sensor is reading.
5. 55. Replace coolant temperature sensor if all checks are normal but error persists.

• Faulty coolant temperature sensor
• Short circuit in the sensor wiring
• Coolant boiling due to low coolant level or overheat condition
• Corrosion or bad connection at the sensor connector

$$ (100-300)