Engine Coolant Temperature Sensor Voltage Above Normal Operating Range
Indicates high voltage from the engine coolant temperature sensor.
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What it means (plain English)
The engine's computer is getting a signal that the coolant temperature sensor is reading much higher than expected, which might mean the sensor is faulty or there's an issue with the wiring.
What the computer is actually seeing
The Engine Control Module (ECM) is receiving a voltage reading from the coolant temperature sensor that exceeds 4.5 volts, which is out of range for a typical operational scenario. Normal operation should see the voltage between 0.5 to 4.5 volts depending on the temperature.
What a healthy reading looks like
The coolant temperature sensor voltage should be between 0.5 volts (around 30°F) to 4.5 volts (around 240°F) during 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 wiring and connectors between the sensor and the ECM for visible damage or corrosion. Can you repair any damage?
- 22. Verify the coolant level; should be at the recommended level. Is it low?
- 33. Using a multimeter, measure the voltage at the sensor connector. Is it above 4.5 volts?
- 44. Inspect and test the coolant temperature sensor. Is the resistance within specifications?
- 55. If all pass, consider testing the ECM for faults.
Common causes
- Faulty coolant temperature sensor
- Shorted wiring to the sensor
- Corroded connectors
- Low coolant level
- Faulty ECM
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It’s recommended to fix it soon, but the vehicle may be drivable unless other symptoms occur.
Will the code come back?
If the underlying issue isn’t resolved, yes, it will likely return.
Why does this code pair with other SPN codes?
Multiple codes often indicate related sensor or wiring issues, or a malfunctioning ECM.
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