What is SPN 656 FMI 7 CUMMINS & How to Solve It?

What is SPN 656 FMI 7:

SPN 656 FMI 7 in Cummins engines refers to a problem with the Engine Coolant Temperature Sensor. FMI 7 indicates that the sensor is sending an out-of-range signal, affecting the ECM’s ability to properly monitor engine coolant temperatures.

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Why This Happens:

• Faulty engine coolant temperature sensor.
  
• Damaged or shorted wiring in the sensor circuit.
  
• Corroded or loose sensor connectors.
  
• Low coolant levels affecting sensor readings.
  
• ECM misinterpretation of the sensor data.
  
  

How to Fix It:

1. Inspect the coolant temperature sensor for damage or malfunction.
   
2. Test the sensor’s signal and ensure it matches manufacturer specifications.
   
3. Check the wiring and connectors for signs of damage, corrosion, or loose connections.
   
4. Replace the faulty sensor if necessary.
   
5. Verify the coolant levels and ensure proper coolant flow.
   
   

How to Avoid It Before It Happens:

• Regularly inspect the coolant temperature sensor and its wiring.
  
• Maintain proper coolant levels and replace coolant as needed.
  
• Keep connectors clean and ensure they are free from corrosion.
  
• Use diagnostic tools to monitor the sensor’s performance.
  
• Clue’s Equipment Maintenance services help track sensor health and prevent overheating or mismanagement of engine coolant systems.