Engine Coolant Temperature Exceeds Normal Operating Range

The sensor measures the coolant temperature, which should normally be between 185°F and 220°F. If it goes above this range, the engine may be overheating, which can cause serious engine damage.

The engine control module (ECM) gets signals from the coolant temperature sensor. If the temperature reading exceeds about 240°F for too long, the code triggers. The ECM will also monitor engine conditions and try to adjust fuel delivery and timing to compensate.

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 in the reservoir and radiator. Add if low. Decision: Is coolant level normal? Yes - proceed to step 2. No - top off and see if code comes back.
2. 22. Inspect for visible leaks in hoses, water pump, and radiator. Decision: Are there leaks? Yes - repair leaks, then clear codes. No - proceed to step 3.
3. 33. Check the operation of the thermostat by starting engine and observing if the upper radiator hose gets hot after about 10-15 minutes. Decision: Does the hose get hot? Yes - proceed to step 4. No - replace thermostat and test again.
4. 44. Test the coolant temperature sensor with a scanner. Compare readings to actual coolant temperature with an infrared thermometer. Decision: Is the sensor reading accurate? Yes - inspect the radiator and coolant passage for blockages. No - replace the coolant temperature sensor.

• Low coolant level
• Coolant leaks
• Faulty coolant temperature sensor
• Stuck thermostat
• Radiator blockage or failure

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