Coolant Temperature Sensor Circuit - High Voltage
The coolant temperature sensor circuit has detected a high voltage issue.
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What it means (plain English)
The computer monitors the coolant temperature with a sensor. If the sensor sends a signal above about 5 volts, it thinks there's a problem, which can tell the engine to run poorly or shut down.
What the computer is actually seeing
The engine control unit (ECU) expects the coolant temperature sensor signal to be between 0.5V (when cold) to 4.5V (when hot). A reading above 5V triggers this code.
What a healthy reading looks like
Coolant temperature sensor should output between 0.5V (0°C) and 4.5V (100°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 wiring and connectors at the coolant temperature sensor for damage or corrosion. If the wiring is okay, proceed to step 2.
- 22. Measure the voltage at the coolant temperature sensor connector with the ignition on, engine off. Voltage should be between 0.5V to 4.5V. If it's above 5V, check for short circuits to voltage sources. If in range, go to step 3.
- 33. Disconnect the sensor and check if the voltage drops to near 0V. If it does, replace the sensor. If it doesn't, the problem could be in the ECU.
Common causes
- Shorted coolant temperature sensor
- Wiring harness issues
- Poor connection at the connector
- Faulty engine control module (ECM)
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; drive with caution but get it fixed soon.
Will this code come back after clearing?
Yes, if the underlying issue isn't resolved, it will likely return.
Why do I see this with low coolant level?
Low coolant can affect the temperature readings, causing sensors to misread and throw a code.
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