Incorrect Engine Cooling Temperature Signal
The engine control unit (ECU) detects a cooling system temperature signal that is out of expected range.
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What it means (plain English)
The engine's computer is getting a temperature reading from the cooling system that doesn't match what it should see, usually too high or too low for the current engine conditions.
What the computer is actually seeing
The ECU expects a coolant temperature between 180°F and 220°F (82°C - 104°C) when the engine is running. If the reading is below 160°F (71°C) or above 230°F (110°C) for more than a few minutes, it triggers the code.
What a healthy reading looks like
Engine coolant temperature should be around 190°F (88°C) during normal operation; acceptable range is 180°F to 220°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 and top off if low. If low, inspect for leaks.
- 22. Inspect the wiring and connectors to the coolant temperature sensor for damage or corrosion. Repair as needed.
- 33. Measure the resistance of the coolant temperature sensor at various temperatures to ensure it operates within expected specs.
- 44. With the engine running, use a scan tool to monitor the live data from the coolant temperature sensor. Compare it against expected values. If it doesn't match, replace the sensor.
- 55. If still active, test the thermostat operation. Ensure it's opening and closing properly during engine warm-up.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issues or poor connections
- Low coolant level or leaks
- Faulty thermostat
- Cooling fan malfunction
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity, so the vehicle may drive but should be addressed soon to avoid overheating or further issues.
Will the check engine light go away on its own?
Not likely. If the issue isn't resolved, the light will remain and possibly cause further engine issues.
Why does this code sometimes pair with other SPN codes?
This often happens if multiple components influence engine temperature, such as the thermostat or additional sensors.
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