Engine Coolant Temperature Sensor - Circuit High
The engine coolant temperature sensor is reporting a high signal to the ECU.
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What it means (plain English)
The coolant temperature sensor measures the temperature of your engine's coolant. When it sends a signal that's higher than normal (like over 250°F or 121°C), the computer thinks there's a problem with the sensor or the engine is overheating, and it throws a code to alert you.
What the computer is actually seeing
The engine control unit (ECU) expects the coolant temperature to be between 185°F (85°C) and 220°F (104°C) during normal operation. A signal higher than 250°F (121°C) from the sensor indicates a fault.
What a healthy reading looks like
Normal coolant temperature readings should be 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 engine coolant level. Ensure it's between the minimum and maximum marks. If low, top it off and see if the code returns.
- 22. Inspect the wiring and connector at the engine coolant temperature sensor for any visible damage or corrosion.
- 33. Using a multimeter, measure the voltage at the coolant temperature sensor connector: you should get a range of 0.5V to 4.5V depending on temperature. If it’s over 4.5V, replace the sensor.
- 44. If the sensor is within specs but the code persists, check the wiring harness for continuity to the ECU, ensuring there's no break.
- 55. If everything checks out but the code remains, consider replacing the engine coolant temperature sensor.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issue between the sensor and ECU
- Corrosion or poor connection at the sensor plug
- Coolant leaks causing low fluid levels
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive with this code as it could lead to overheating, which can cause serious engine damage.
Will this code come back after clearing?
It may return if the underlying issue isn't fixed, especially if there's a fault in the sensor or wiring.
Why does this code pair with other codes?
Multiple codes can indicate related issues, like sensor problems affecting various systems or multiple components failing.
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