Engine Coolant Temperature Sensor Voltage Out of Range
The engine coolant temperature sensor is reporting a voltage that is outside the expected range.
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What it means (plain English)
The engine coolant temperature sensor measures how hot the engine coolant is. When it's not working right, it sends signals that are too high or too low, which can make the engine run poorly.
What the computer is actually seeing
The computer is receiving voltage from the coolant temperature sensor that is significantly below 0.5 volts or above 4.5 volts, when it should be in a range between these values during normal operation.
What a healthy reading looks like
Normal operating voltage from the coolant temperature sensor should range between 0.5 to 4.5 volts depending on coolant temperature, which can be approximately 100 degrees Celsius (212 degrees Fahrenheit) for around 2.5 volts.
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 engine coolant level. Ensure it's at the proper level to avoid sensor malfunction. Decision: Is coolant level okay? (Yes: proceed, No: top-up and see if code clears)
- 22. Inspect the connector and wiring to the coolant temperature sensor. Look for damage, corrosion, or loose connections. Decision: Is wiring intact? (Yes: proceed, No: repair/replace wiring and retest)
- 33. Using a multimeter, measure the voltage at the coolant temperature sensor while the engine is running. Check for voltage within 0.5 - 4.5 volts. Decision: Is voltage in range? (Yes: sensor may be fine, No: proceed to next step)
- 44. Replace the coolant temperature sensor if voltage is out of the expected range.
- 55. Clear the fault code and test drive the vehicle to see if it returns. If it does, consider ECM issues.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or shorts in the sensor circuit
- Corroded connectors
- Coolant leaks affecting sensor function
- Faulty Engine Control Module (ECM)
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Moderate severity means you can drive but should fix soon to avoid overheating or poor engine performance.
Will the code come back after clearing it?
If the underlying issue isn't fixed, yes, it will return.
Why does this code pair with others like SPN 6798?
Different codes can indicate related sensor faults, like issues with temperature readings affecting multiple systems.
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