What is SPN 2791 FMI 14 & How to Solve It?

What is SPN 2791 FMI 14:

SPN 2791 FMI 14 indicates a fault with the Selective Catalytic Reduction (SCR) Urea Dosing Valve Circuit Malfunction. This code means the engine control module (ECM) has detected a communication or signal problem with the urea dosing valve, which is responsible for injecting Diesel Exhaust Fluid (DEF) into the exhaust to reduce harmful nitrogen oxide emissions.

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Why This Happens

Common causes include:

• Faulty or damaged urea dosing valve.
  
• Wiring issues such as shorts, open circuits, or damaged connectors.
  
• Contaminated or degraded DEF fluid affecting valve operation.
  
• Faulty Engine Control Module (ECM) or sensor calibration issues.

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How to Fix It

To resolve this fault:

1. Inspect the urea dosing valve and wiring for damage or corrosion.
   
2. Test the valve for proper operation and replace if faulty.
   
3. Replace contaminated DEF fluid if necessary.
   
4. Repair or replace damaged wiring or connectors.
   
5. Clear the fault code and monitor system performance.
   
   

How to Avoid It Before It Happens

Prevent this fault by:

• Using high-quality DEF fluid and changing it regularly.
  
• Regularly inspecting the urea dosing valve and wiring.
  
• Keeping the DEF system clean and well-maintained.
• Use Clue’s Preventive Maintenance to schedule regular inspections of the urea dosing valve and DEF system to ensure optimal performance and prevent malfunctions.