What is SPN 792 FMI 5 & How to Solve It?

What is SPN 792 FMI 5:

SPN 792 FMI 5 indicates a fault with the Boost Pressure Sensor Circuit – Signal Too Low. This means the engine control module (ECM) is detecting a lower-than-expected signal from the boost pressure sensor, which monitors the pressure of the air entering the engine’s intake manifold. Accurate readings are essential for optimizing engine performance and fuel efficiency.

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Why This Happens

Common causes include:

• Faulty or failing boost pressure sensor.
  
• Damaged, loose, or corroded wiring/connectors in the sensor circuit.
  
• Leaks or restrictions in the intake system affecting pressure readings.
  
• Faulty ECM or sensor calibration errors.
  
  

How to Fix It

To resolve this fault:

1. Inspect the boost pressure sensor and wiring for damage or corrosion.
   
2. Check the intake system for leaks or restrictions.
   
3. Test the sensor output and replace if faulty.
   
4. Repair or replace damaged wiring or connectors.
   
5. Clear the fault code and verify sensor readings.
   
   

How to Avoid It Before It Happens

Prevent this fault by:

• Regularly inspecting the boost pressure sensor and intake system.
  
• Maintaining a sealed intake system free of leaks.
  
• Performing routine diagnostics to catch sensor or wiring issues early.
• Leverage Clue’s Asset Tracking to monitor the boost pressure sensor and intake system in real-time, helping detect issues early and optimize engine performance.