Engine Coolant Temperature Too High
The engine's coolant temperature is higher than expected.
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What it means (plain English)
The engine’s coolant temperature sensor is reading above the normal operating range, which is typically above 240°F (116°C). This can indicate that the engine is overheating or that there is a problem with the cooling system.
What the computer is actually seeing
The engine control unit (ECU) monitors the coolant temperature sensor signal, which should fluctuate between 180°F (82°C) and 220°F (104°C) during normal operation. A reading exceeding 240°F (116°C) triggers the fault code.
What a healthy reading looks like
Normal coolant temperature readings should range from 180°F (82°C) to 220°F (104°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. Is it below minimum? (Yes - refill and test again, No - continue to next step)
- 22. Inspect the wiring and connector at the coolant temperature sensor for damage or corrosion. Is there any visible issue? (Yes - repair or replace as necessary, No - continue to next step)
- 33. Start the engine and monitor the coolant temperature using a scanner or temperature gauge. Is it exceeding 240°F (116°C)? (Yes - continue to next step, No - the code may be intermittent or resolved)
- 44. Check the operation of the thermostat. Is it stuck closed or not opening? (Yes - replace the thermostat, No - continue to next step)
- 55. Check the performance of the cooling fan. Is it functioning correctly? (No - replace or repair fan, Yes - may need further diagnosis)
Common causes
- Low coolant level
- Faulty thermostat
- Failed radiator or cooling fan
- Blocked radiator
- Failed coolant temperature sensor
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving with an overheating engine can cause severe damage and should be addressed immediately.
Will the code come back after a reset?
If the underlying issue is not resolved, the code will likely return.
Why does this code pair with others?
Related codes typically indicate similar or interconnected issues within the engine cooling system.
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