Engine Coolant Temperature Too High

The engine management system checks the coolant temperature sensor. If the coolant gets too hot, it sends a signal to the computer that it’s overheating—usually above 240°F (115°C) which can damage the engine.

The engine control unit (ECU) is monitoring the coolant temperature signal, looking for values above approximately 240°F (115°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 the coolant level in the reservoir; ensure it's between the minimum and maximum marks. If low, top off with the correct type and 50/50 mix.
2. 22. Inspect for visible leaks in hoses, radiator, and connections. Repair any leaks found.
3. 33. Start the engine and allow it to run until the temperature stabilizes. Use a scan tool to monitor the coolant temperature reading. Is it above 240°F (115°C)? If not, code is likely intermittent or caused by wiring issues.
4. 44. Check the operation of the thermostat by running the engine to temperature; a stuck closed thermostat will prevent coolant flow and cause overheating. Replace if necessary.
5. 55. Test the coolant temperature sensor with a multimeter. Check that resistance changes with temperature (should be about 2500 ohms at 77°F (25°C)). Replace if readings are outside normal range.

• Low coolant level
• Cooling system leaks
• Faulty thermostat
• Failed water pump
• Clogged radiator
• Malfunctioning coolant temperature sensor

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