Engine Coolant Temperature Sensor - Voltage Above Normal
The engine coolant temperature sensor is sending a high voltage signal.
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What it means (plain English)
The engine coolant temperature sensor measures how hot the engine coolant is. When it's too high, it means the engine might be overheating or the sensor is malfunctioning, sending a faulty high voltage signal back to the engine computer.
What the computer is actually seeing
The engine control unit (ECU) sees a voltage reading from the coolant temperature sensor that exceeds the normal range, usually above 4.5 volts for diesel systems.
What a healthy reading looks like
Normal voltage should be between 0.5 to 4.5 volts, with the typical reading around 1.5 volts at normal operating temperature.
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 to the coolant temperature sensor for damage or corrosion. Repair if necessary.
- 22. Measure the voltage at the coolant temperature sensor connector with the ignition on and engine off. It should be between 0.5 to 4.5 volts. If it's above 4.5 volts, check wiring for a short to power.
- 33. If wiring checks out, replace the coolant temperature sensor and retest.
- 44. Clear the fault codes and run the engine to check for the return of the SPN 1507 code. If the code comes back, check for overheating or other related engine issues.
Common causes
- Faulty coolant temperature sensor
- Wiring issues (short to power)
- Corroded or loose connectors
- Coolant on sensor causing incorrect readings
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Moderate severity indicates you should fix it soon, as overheating could cause engine damage.
Will this code come back after I fix it?
If you address the faulty sensor and check wiring, it should not return.
Why does this code pair with other codes?
Often, issues with temperature sensors can also trigger related fault codes for other monitoring systems.
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