What is SPN 3563 FMI 21 & How to Solve It?

What is SPN 3563 FMI 21:

SPN 3563 FMI 21 refers to a high voltage condition in the Turbocharger Boost Pressure Sensor Circuit. FMI 21 indicates that the ECM is receiving a voltage higher than expected, which could affect the turbocharger’s ability to manage boost pressure and reduce engine performance.

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Why This Happens:

• Faulty turbocharger boost pressure sensor.
  
• Shorted or damaged wiring in the sensor circuit.
  
• High voltage supply affecting the sensor’s output.
  
• Loose or corroded sensor connectors.
  
• ECM misinterpreting the sensor’s signal.
  
  

How to Fix It:

1. Inspect the turbocharger boost pressure sensor for any visible damage.
   
2. Test the sensor’s voltage and resistance to verify it is within specifications.
   
3. Check the wiring and connectors for visible damage or corrosion.
   
4. Replace the faulty sensor if necessary.
   
5. Inspect the turbocharger system for any mechanical issues.
   
   

How to Avoid It Before It Happens:

• Regularly inspect the turbocharger boost pressure sensor and wiring.
  
• Maintain the turbocharger system to ensure optimal performance.
  
• Keep connectors clean and free from corrosion.
  
• Use diagnostic tools to monitor turbo system performance.
  
• Clue’s Equipment Maintenance services monitor turbocharger boost pressure to help prevent sensor-related issues from affecting engine operation.