Engine Coolant Temperature Sensor - High Voltage
The engine coolant temperature sensor is reading a voltage level that is higher than expected.
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What it means (plain English)
The coolant temperature sensor should provide a signal around 0.5 to 4.5 volts based on temperature. If it goes above 4.5 volts, the computer thinks there’s a problem and triggers this code.
What the computer is actually seeing
The Engine Control Module (ECM) detects that the coolant temperature sensor output voltage is too high, indicating a potential short circuit or sensor malfunction.
What a healthy reading looks like
Normal operation voltage should range from 0.5V at -40°C to approximately 4.5V at 140°C; higher than 4.5V is considered a fault.
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 of the coolant temperature sensor for damage or corrosion. - If damaged, repair or replace wiring/connector.
- 22. Measure the voltage at the coolant temperature sensor connector with the ignition on and engine off. - If over 4.5 volts, suspect a short circuit. Proceed to step 3.
- 33. Disconnect the coolant temperature sensor and re-measure the voltage at the connector with the sensor unplugged. - If voltage drops back to expected range, replace the coolant temperature sensor.
- 44. Check for any wiring shorts to power sources or insulation failures. - If shorts found, repair wiring. If no issues found, recheck sensor operation.
Common causes
- Shorted wiring in sensor circuit
- Faulty engine coolant temperature sensor
- Poor electrical connections
- Infared radiation interference from exhaust components
Typical repair cost
$$$
Related codes
Frequently asked questions
Can I drive with this code active?
It's not safe to drive if the engine is overheating or if it's causing performance issues, get it checked soon.
Will the code come back after clearing it?
If the underlying issue is not fixed, it will likely return after clearing and running the vehicle.
Does this code relate to the thermostat?
Not directly, but if the coolant sensor is faulty, it might not give accurate temperature readings affecting thermostat behavior.
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