What is SPN 636 FMI 2 & How to Solve It?

What is SPN 636 FMI 2:

SPN 636 FMI 2 refers to a fault in the Crankshaft Position Sensor Circuit. FMI 2 indicates that the ECM has detected an abnormal signal from the sensor, which could result in poor engine performance, misfires, or difficulty starting the engine.

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Why This Happens:

• Faulty crankshaft position sensor.
  
• Damaged or shorted wiring in the sensor circuit.
  
• Corroded or loose sensor connectors.
  
• Poor ECM communication with the sensor.
  
• Incorrect installation of the crankshaft sensor.
  
  

How to Fix It:

1. Inspect the crankshaft position sensor for damage or malfunction.
   
2. Test the sensor’s signal and resistance to ensure it is functioning properly.
   
3. Check wiring and connectors for signs of wear or corrosion.
   
4. Replace the faulty crankshaft position sensor.
   
5. Inspect the ECM for proper communication with the sensor.
   
   

How to Avoid It Before It Happens:

• Regularly inspect the crankshaft position sensor and its wiring.
  
• Keep connectors clean and free from corrosion.
  
• Ensure proper installation of the sensor.
  
• Perform routine diagnostic checks to ensure sensor functionality.
  
• Clue’s Equipment Maintenance services can help monitor sensor performance and address potential failures before they cause issues.