What is SPN 925 FMI 5:
SPN 925 FMI 5 refers to a problem with the Engine Coolant Temperature Sensor. FMI 5 indicates that the ECM has detected an out-of-range signal from the sensor, likely due to a high voltage condition, which may lead to inaccurate coolant temperature readings, potentially causing engine overheating or improper engine management.
Why This Happens:
- Faulty engine coolant temperature sensor.
- Damaged or shorted wiring in the sensor circuit.
- Loose or corroded sensor connectors.
- Low coolant levels affecting sensor readings.
- ECM failure to interpret the sensor’s data correctly.
How to Fix It:
- Inspect the engine coolant temperature sensor for visible damage or malfunction.
- Test the sensor’s voltage and resistance to ensure it falls within manufacturer specifications.
- Check the wiring and connectors for visible damage, corrosion, or loose connections.
- Replace the faulty coolant temperature sensor if it is malfunctioning.
- Ensure that the coolant levels are correct and the cooling system is functioning properly.
How to Avoid It Before It Happens:
- Regularly inspect the engine coolant temperature sensor and wiring.
- Keep connectors clean and free from corrosion or moisture.
- Ensure proper coolant levels are maintained and the system is regularly serviced.
- Perform routine diagnostic checks to monitor sensor accuracy and coolant system health.
- Clue’s Equipment Maintenance services help monitor coolant temperature sensors and prevent overheating or mismanagement issues before they arise.
