What is SPN 629 FMI 12 & How to Solve It?

What is SPN 629 FMI 12:

SPN 629 FMI 12 refers to an issue with the Fuel System Pressure Sensor. FMI 12 indicates that the ECM is receiving a signal from the fuel system pressure sensor that is out of the expected range, leading to incorrect fuel pressure readings and potentially poor engine performance.

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Why This Happens:

• Faulty fuel system pressure sensor.
  
• Shorted or damaged wiring in the sensor circuit.
  
• Loose or corroded sensor connectors.
  
• Low fuel pressure due to a malfunctioning fuel pump.
  
• ECM misinterpreting the sensor’s data.
  
  

How to Fix It:

1. Inspect the fuel system pressure sensor for visible damage or malfunction.
   
2. Test the sensor’s voltage and resistance to verify it matches specifications.
   
3. Check wiring and connectors for corrosion or loose connections.
   
4. Replace the faulty fuel system pressure sensor if necessary.
   
5. Inspect the fuel system for low pressure or a malfunctioning fuel pump.

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How to Avoid It Before It Happens:

• Regularly inspect the fuel system pressure sensor and wiring.
  
• Keep connectors clean and free from corrosion.
  
• Maintain proper fuel pressure and replace filters as needed.
  
• Perform regular diagnostic checks to monitor fuel pressure.
  
• Clue’s Fuel Management services help track fuel pressure and prevent malfunctions before they impact engine performance.