What is SPN 3251 FMI 4 & How to Solve It?

What is SPN 3251 FMI 4:

SPN 3251 FMI 4 refers to a low voltage condition in the Fuel Pressure Sensor Circuit. FMI 4 means the ECM is receiving a signal that is below the expected level, which can cause incorrect fuel pressure readings and lead to engine performance issues such as poor acceleration or stalling.

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Why This Happens:

• Faulty fuel 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 misinterpretation of the sensor’s data.
  
  

How to Fix It:

1. Inspect the fuel pressure sensor for any visible damage or malfunction.
   
2. Test the sensor’s voltage and resistance to ensure it is within specification.
   
3. Check wiring and connectors for visible damage, corrosion, or loose connections.
   
4. Replace the faulty fuel pressure sensor if necessary.
   
5. Inspect the fuel system for low fuel pressure or pump issues.
   
   

How to Avoid It Before It Happens:

• Regularly inspect the fuel pressure sensor and wiring.
  
• Maintain proper fuel pressure and replace fuel filters regularly.
  
• Keep connectors clean and corrosion-free.
  
• Perform diagnostic checks to monitor sensor performance.
  
• Clue’s Fuel Management services help monitor fuel pressure and proactively detect issues before they affect engine performance.