Engine Coolant Temperature Sensor
Thermocouple reading for engine coolant temperature is out of range.
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What it means (plain English)
The engine is monitoring the temperature of the coolant, and it has detected that the temperature sensor is giving readings that are too high or too low, meaning the engine's cooling system might not be working as it should.
What the computer is actually seeing
The engine computer expects the coolant temperature to be between 185°F and 220°F (85°C to 104°C) during normal operating conditions, and it flags a fault when the input goes outside this range.
What a healthy reading looks like
Coolant temperature should typically range between 185°F (85°C) and 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. If low, refill and retest.
- 22. Inspect wiring and connector to the coolant temperature sensor for damage or corrosion. Repair as needed and retest.
- 33. Use a scan tool to check real-time data. Compare coolant temperature reading to engine operating temperature. If the sensor reading is inaccurate, go to step 4.
- 44. Replace the coolant temperature sensor with a new one (ensure you have the right part). Clear codes and retest.
- 55. If the code returns after replacing the sensor, check the engine thermostat function — it should open around 195°F (90°C). Ensure there are no coolant flow restrictions.
Common causes
- Faulty coolant temperature sensor
- Bad wiring or connections to the sensor
- Low coolant level
- Faulty engine thermostat
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to fix it soon as overheating can cause engine damage.
Will this code come back after repair?
If you fix the root cause, it shouldn't return.
Why does this code sometimes appear with low coolant?
Low coolant can cause inaccurate readings; fix leaks or top off coolant first.
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