Coolant Temperature Sensor Voltage High
The coolant temperature sensor signal is too high.
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What it means (plain English)
The engine computer measures the coolant temperature using a sensor. If that sensor sends a signal that’s too high, it means the engine thinks it's overheating.
What the computer is actually seeing
The engine control module expects the coolant temperature to be between 180°F and 220°F (82°C to 105°C). If the voltage from the sensor exceeds 4.5 volts, it triggers this code.
What a healthy reading looks like
Coolant temperature should normally create a voltage between 0.5 to 4.5 volts; anything above 4.5 volts is considered too high.
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. Is it low? If yes, refill and recheck for codes.
- 22. Inspect the wiring and connectors at the coolant temperature sensor. Are there any visible damages or corrosion? If yes, repair the wiring and recheck.
- 33. Use a multimeter to test the coolant temperature sensor output. Is it above 4.5 volts while the engine is at a normal operating temperature? If yes, replace the sensor.
- 44. If the sensor checks out, connect a scan tool and monitor coolant temperature readings live. Do they match the actual engine temperature? If no, consider replacing the ECU.
Common causes
- Faulty coolant temperature sensor
- Wiring short circuit to voltage
- Open circuit in the wiring
- Engine coolant leak causing high temperature
- Faulty engine control module
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best not to drive the vehicle since it thinks the engine is overheating, which could cause damage.
Will the code come back after repairs?
If the issue is fixed properly, the code should not return.
Why is this code paired with coolant issues?
Because a high voltage reading indicates coolant temperature is not being accurately sensed, often due to sensor failure or wiring faults.
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