Engine Coolant Temperature Sensor Circuit High
The engine coolant temperature sensor is reading a voltage that exceeds the expected range.
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What it means (plain English)
The sensor that reads your engine's coolant temperature is sending a signal that’s too high, meaning it thinks the engine is hotter than it really is.
What the computer is actually seeing
The control module expects the coolant temperature signal to be between 0.5V (approx. -40°C / -40°F) to 4.5V (approx. 125°C / 257°F). When it sees a voltage higher than 4.5V, it triggers this fault.
What a healthy reading looks like
Coolant temperature signals should be between 0.5V and 4.5V for normal operation.
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 off and retest.
- 22. Inspect the wiring and connector for damage or corrosion. Repair or replace as necessary.
- 33. Measure the voltage at the coolant temperature sensor connector. Expect 0.5V to 4.5V with engine at different temperatures.
- 44. If voltage is above 4.5V, backprobe while wiggling the harness to find a short. If the signal drops, fix the wiring issue.
- 55. If voltage is normal but the code persists, replace the coolant temperature sensor and clear the code.
Common causes
- Shorted sensor wiring
- Faulty coolant temperature sensor
- Poor connection at the sensor or wiring harness
- Corrupted data signal due to electrical interference
- Open circuit in the connector
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally safe to drive, but engine performance may be affected, especially in extreme conditions.
Will this fault code come back after I fix it?
If the underlying issue is resolved, the code should not return.
Why does this code appear with others?
This sensor often fails alongside others due to shared wiring or similar wear factors.
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