Coolant Temperature Above Normal Operating Range

The engine is running too hot, which could lead to overheating. This is usually due to coolant not circulating properly or an issue with the thermostat.

The engine control module monitors the coolant temperature sensor, which sends voltage signals based on the engine's heat. A voltage reading above 2.5V (typically represents a coolant temperature above 230°F) triggers this fault.

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 the coolant level in the reservoir. Is it low? If yes, top it off and retest. If not low, proceed to step 2.
2. 22. Inspect the wiring and connector to the coolant temperature sensor. Are there any visible signs of damage or corrosion? If so, repair or replace as needed. If the wiring is good, proceed to step 3.
3. 33. Test the coolant temperature sensor with a multimeter. At 200°F, it should read about 2.0V. Does it match expected values? If not, replace sensor and retest. If it does match, proceed to step 4.
4. 44. Check the thermostat operation. Does the engine stay cool when idling for 10 minutes and heats up rapidly during driving? If it's stuck closed, replace the thermostat. If thermostat is good, proceed to step 5.
5. 55. Inspect the radiator for blockages or leaks. Is it clear and functioning? If blocked, clean or replace as necessary. If all checks pass, further testing may be required on the water pump.

• Low coolant level
• Faulty coolant temperature sensor
• Thermostat stuck closed
• Blocked radiator
• Water pump failure

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