Engine Coolant Temperature Sensor Voltage High
The engine coolant temperature sensor voltage is higher than normal.
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What it means (plain English)
The engine computer expects the coolant temperature reading to be between 180°F and 220°F. If the sensor is reading over 255°F, it flags a high voltage issue. This could mean the sensor is faulty or there's a wiring problem.
What the computer is actually seeing
The engine control module (ECM) reads a coolant temperature of 255°F or higher from the sensor, indicating an open circuit or short to high voltage.
What a healthy reading looks like
Coolant temperature readings should typically be between 180°F and 220°F; a valid sensor voltage should be between 0.5V (low temp) and 4.5V (high temp).
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.
- 1Check the engine coolant level; ensure it's within the normal range. If low, top it off and retest. Decision: If code returns, proceed to the next step.
- 2Inspect the wiring and connectors at the coolant temperature sensor for any damage or corrosion. Fix as necessary. Decision: If all appears good, continue to next step.
- 3Test the voltage at the coolant temperature sensor connector. It should be between 0.5V and 4.5V with the ignition on, engine off. Decision: If voltage is outside this range, replace the sensor. If within range, check the ECM.
- 4Remove the coolant temperature sensor and test it in a temperature-controlled environment to see if it sends the correct voltage back at specified temperatures. Decision: If sensor fails test, replace it.
Common causes
- Faulty engine coolant temperature sensor
- Open circuit in the sensor wiring
- Shorted wiring to the sensor
- Corroded connectors
- Low coolant level affecting sensor performance
Typical repair cost
$$ (100-300)
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable, but overheating could happen; fix soon to avoid further damage.
Will this code come back after clearing?
If the underlying issue isn't resolved, it will likely return.
Why does this code pair with other SPN codes?
They may relate to engine temp issues or sensor malfunctions, indicating interconnected faults.
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