Engine Coolant Temperature Sensor Circuit Low
The engine coolant temperature sensor signal is too low, indicating possible overheating or sensor failure.
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What it means (plain English)
The coolant temperature sensor, which tells the engine how hot the coolant is, is sending a signal below 0.1 volts. This can lead the engine to think it’s cold and not run correctly.
What the computer is actually seeing
The electronic control unit (ECU) expects a voltage signal from the coolant temperature sensor to be between 0.5 and 4.5 volts. A reading below 0.1 volts indicates a potential fault.
What a healthy reading looks like
Normal coolant temperature readings should result in a voltage signal from the sensor between 0.5 to 4.5 volts, corresponding to temperatures from -40 °F to 248 °F.
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. Is it low? If yes, top off the coolant and recheck the code. If no, proceed to step 2.
- 22. Inspect the wiring and connector to the coolant temperature sensor. Are there any signs of damage or corrosion? If yes, repair/replace the wiring or connector. If no, proceed to step 3.
- 33. Use a multimeter to test the voltage at the coolant temperature sensor connector with the engine running. Is the voltage below 0.1 volts? If yes, replace the coolant temperature sensor. If no, proceed to step 4.
- 44. Check the ECU for proper operation and any related fault codes. Are there additional codes present? If yes, diagnose those codes first. If no, further inspect the ECU and consider reprogramming or replacing.
Common causes
- Faulty coolant temperature sensor
- Damaged wiring or connector
- Low coolant level
- Shorted wiring to sensor
- ECU calibration issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best not to drive for long distances, as it may cause engine overheating or performance issues.
Will this code come back after clearing it?
If the underlying issue isn't fixed, the code will likely return.
Why does this code sometimes pair with SPN 0026?
SPN 0026 is related to the coolant temperature sensor circuit high, which can be triggered by similar issues such as sensor failure or wiring problems.
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