Engine Coolant Temperature Sensor 1

The coolant temperature sensor is like a thermometer for the engine, telling the computer how hot the engine is. If it reads too high or too low, the computer gets confused.

The engine control module (ECM) sees the coolant temperature values from the sensor and expects them to fall within a normal range. If it detects values outside of this range (below 80ºC or above 120ºC), it will trigger this code.

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.

1. 11. Check coolant level in the reservoir. Ensure it's at or above the minimum level. If low, refill and retest.
2. 22. Inspect the wiring and connectors to the coolant temperature sensor for any damage or corrosion. Repair as necessary.
3. 33. Using a scan tool, monitor the coolant temperature while the engine is running. Compare the reading to actual engine temperature (use a laser thermometer for accuracy). If values are inconsistent, the sensor may need replacement.
4. 44. If the sensor appears faulty, replace it and clear the code. After replacement, monitor for any reoccurrence of the code.

• Faulty coolant temperature sensor
• Wiring issues or short circuits in the sensor circuit
• Low coolant level causing inaccurate readings
• Corrosion or poor connection at the sensor connector

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