Engine Coolant Temperature Sensor 2

There are two coolant temperature sensors in the engine. The second one is either reading too high or too low compared to normal values, which affects how the computer controls engine temperatures.

The engine control module (ECM) expects the second coolant temperature sensor to show a certain range of resistance values (typically 0.5 to 4.5 volts depending on the temperature); if it is outside this range, the code triggers.

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 the wiring and connector to coolant temperature sensor 2 for damage or corrosion. Repair as needed.
2. 22. Measure the voltage at the sensor connector with the ignition on (engine off). Expect around 2.5 volts at 195°F. If it's outside of expected values, replace the sensor.
3. 33. Inspect for any coolant leaks that could affect sensor operation. Fix leaks before further testing.
4. 44. Clear the code and run the engine to see if the code returns. If it does, consider testing the ECM if all else checks out.
5. 55. If after replacing the sensor the problem persists, check for issues with the primary coolant temperature sensor.

• Faulty coolant temperature sensor 2
• Wiring issues or poor connections
• Coolant leaks affecting the sensor
• ECM faults

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