Engine Coolant Temperature Too High
The engine's coolant temperature is excessive.
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What it means (plain English)
The engine computer is seeing that the engine coolant is running hotter than 220°F (104°C), which can cause overheating and potential engine damage.
What the computer is actually seeing
The engine control module (ECM) receives signals from the coolant temperature sensor indicating temperatures that exceed 220°F (104°C).
What a healthy reading looks like
Engine coolant temperature should typically be between 190°F and 215°F (88°C and 102°C).
Guided diagnostic — the DiagCoach way
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.
- 11. Check the coolant level in the reservoir. If low, top it off and observe if the problem persists.
- 22. Inspect the coolant temperature sensor connector for corrosion or loose connections. If damaged, repair or replace the connector.
- 33. Measure the coolant temperature using a digital thermometer at the radiator outlet. It should match the ECM readings within 5°F (3°C). If it's significantly different, replace the coolant temperature sensor.
- 44. Test the thermostat by checking the temperature of the upper radiator hose. If it doesn't open (hose remains cold) by 195°F (91°C), replace the thermostat.
- 55. Inspect for external leaks around the radiator, hoses, and water pump. Repair as needed and check coolant flow.
- 66. If everything checks out and the code persists, inspect the water pump for proper operation (no strange noises or leaks). Replace if faulty.
Common causes
- Coolant level low
- Faulty coolant temperature sensor
- Thermostat stuck closed
- Radiator blockage or leak
- Water pump failure
Typical repair cost
$$$ (300-600)
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not safe to drive if the engine is overheating as it can cause serious damage.
Will this code come back after clearing it?
If the underlying issue isn't fixed, the code will likely return.
Why does this code appear with other codes?
High coolant temperature can affect multiple systems, leading to related fault codes.
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