What is SPN 5246 FMI 16 & How to Solve It? (Cummins)

What is SPN 5246 FMI 16:

SPN 5246 FMI 16 on Cummins engines refers to a Diesel Exhaust Fluid (DEF) Pressure Sensor Circuit Malfunction. FMI 16 specifically indicates that there is an electrical fault in the DEF pressure sensor circuit, typically related to high resistance or an open circuit. The DEF pressure sensor monitors the pressure within the DEF system, which is crucial for controlling the amount of Diesel Exhaust Fluid injected into the exhaust for emissions reduction.

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Why This Happens

Common causes of SPN 5246 FMI 16 include:

• Faulty DEF pressure sensor.
  
• Wiring issues such as open circuits, shorts, or poor electrical connections.
  
• Corroded or damaged connectors in the sensor circuit.
  
• Faulty ECM or software issues.
  
• Contamination or buildup affecting the sensor.
  
  

How to Fix It

To resolve this fault:

1. Inspect the DEF pressure sensor and wiring for damage or corrosion.
   
2. Check connectors for secure connections and clean any corrosion.
   
3. Test the sensor for proper voltage and resistance; replace it if faulty.
   
4. Inspect the ECM for errors and perform any required software updates.
   
5. Clear the fault code and monitor the DEF system for correct operation.
   
   

How to Avoid It Before It Happens

To prevent this fault:

• Regularly check the DEF pressure sensor and wiring during routine maintenance.
  
• Keep connectors clean and corrosion-free.
  
• Use high-quality DEF fluid and follow manufacturer guidelines.
• Use Clue’s Preventive Maintenance to regularly inspect the DEF pressure sensor and wiring, ensuring all components are in optimal condition and early issues are identified.
  

Perform routine diagnostics to detect early issues in the DEF system.