Engine Coolant Temperature Sensor Circuit High
Indicates a high voltage reading from the engine coolant temperature sensor.
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What it means (plain English)
The engine coolant temperature sensor monitors the temperature of the engine coolant, and a high voltage means it's reading a hotter than expected temperature, possibly signaling an issue with the sensor or the wiring.
What the computer is actually seeing
The engine control module (ECM) receives a voltage signal from the coolant temperature sensor. The expected voltage range is typically around 0.5V to 4.5V, which correlates to a temperature range of -40°C to 125°C. A voltage above 4.5V might trigger this code.
What a healthy reading looks like
Expected voltage from the coolant temperature sensor is between 0.5V (cold) to 4.5V (hot); corresponds to temperatures from -40°C to 125°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. Inspect the wiring and connectors to the engine coolant temperature sensor. Check for any visible damage or corrosion. If found, repair or replace as necessary.
- 22. Measure the voltage at the coolant temperature sensor connector with the engine running but at operating temperature. Expected value should be between 0.5V and 4.5V. If voltage is above 4.5V, proceed to the next step.
- 33. Disconnect the coolant temperature sensor and measure resistance across the sensor terminals. Compare resistance values to a known good sensor or manufacturer specifications. If resistance is out of range, replace the sensor.
- 44. If the sensor checks out, re-test the wiring from the ECM to the sensor for shorts or opens. Use a multimeter to check continuity. Repair as needed.
Common causes
- Short in the sensor wiring
- Faulty coolant temperature sensor
- Poor connection at the sensor or ECM
- Corroded or damaged connectors
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best not to drive long distances with this code due to potential overheating issues.
Will this issue come back after repairs?
If properly diagnosed and repaired, this issue should not return unless there's a new fault.
Why does this code sometimes appear with other codes?
Intermittent faults in wiring or a faulty sensor can lead to multiple fault codes being logged.
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