Engine Coolant Temperature Sensor Out of Range
The engine coolant temperature sensor is reporting temperatures outside of expected limits.
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What it means (plain English)
The engine coolant temperature sensor measures the coolant's temperature to help control engine functions. If it reads too hot, too cold, or fails, it disrupts how the engine runs, potentially causing overheating or poor performance.
What the computer is actually seeing
The engine control module (ECM) expects the coolant temperature to be within a specific range, typically 160°F to 220°F. If the reading is below 140°F or above 240°F, the ECM flags the sensor as out of range, indicating a fault.
What a healthy reading looks like
Engine coolant temperature should be between 160°F and 220°F during normal operation.
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 engine coolant level; ensure it’s at the proper level (between 'MIN' and 'MAX'). If low, top it off and see if the code returns.
- 22. Inspect wiring and connectors for the coolant temperature sensor for damage, corrosion, or loose connections. Repair as necessary and clear the code.
- 33. Use a scan tool to monitor coolant temperature while the engine runs. Compare actual temperature to the readings from the sensor. If readings differ significantly, replace the sensor.
- 44. If the sensor is replaced and the code returns, check for proper voltage supply to the sensor (typically 5V) and ground connections. If faulty, repair the wiring.
- 55. If still no success, consider testing the ECM for faults; reflash if needed.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or connector problems
- Coolant level too low
- Thermostat stuck open or closed
- Faulty engine control module (ECM)
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It can be safe, but monitor your engine temperature closely. If the engine overheats, pull over immediately.
Will this code come back after clearing?
Yes, if the underlying issue isn't fixed, the code will likely return.
Why does this code sometimes pair with SPN 2665?
SPN 2665 is related to a fault in the coolant temperature circuit, often indicating similar wiring or sensor issues.
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