Engine Coolant Temperature
The Engine Control Module has detected an abnormal coolant temperature signal.
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What it means (plain English)
The engine control module (ECM) is getting temperature readings from the coolant temperature sensor that are outside the normal range, meaning the engine might be overheating or the sensor might be faulty.
What the computer is actually seeing
The ECM sees voltage signals from the coolant temperature sensor fluctuating outside the expected range, usually above 255 degrees Fahrenheit or below 32 degrees Fahrenheit.
What a healthy reading looks like
Normal coolant temperature should be between 180°F and 220°F (82°C to 104°C).
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. It should be at or near the full mark.
- 22. Inspect the wiring and connectors to the coolant temperature sensor for damage or corrosion.
- 33. Use a scan tool to read the current coolant temperature and compare it to the actual coolant temperature using a thermometer.
- 44. If the readings are significantly different, replace the coolant temperature sensor.
- 55. If the sensor looks fine, test the wiring for voltage and continuity; it should have around 5 volts when the engine is running.
- 66. If wiring is good, consider checking the thermostat and ensuring it is functioning properly.
Common causes
- Faulty coolant temperature sensor
- Wiring or connector issues
- Low coolant level
- Thermostat failure
- Coolant leaks
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to address this code soon. Driving with an overheating engine can cause serious damage.
Will this code come back after clearing it?
If the problem isn't fixed, the code will likely set again once the engine operates.
Why do I see this code with others like SPN 190?
These codes often relate to the same system (e.g., cooling issues), so they can trigger together.
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