What is SPN 5298 FMI 14 & How to Solve It?

What is SPN 5298 FMI 14:

SPN 5298 FMI 14 indicates a fault with the Selective Catalytic Reduction (SCR) NOx Sensor Circuit – Data Valid But Above Normal Operating Range. This means the sensor is sending a signal that is higher than the expected range, which can affect the efficiency of the SCR system used to reduce nitrogen oxide (NOx) emissions from the engine.

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Why This Happens

Common causes include:

• Faulty or damaged NOx sensor.
  
• Wiring issues such as short circuits, damage, or corrosion.
  
• Interference or contamination affecting the sensor's operation.
  
• Faulty Engine Control Module (ECM) misinterpreting the sensor data.
  
  

How to Fix It

To resolve this fault:

1. Inspect the NOx sensor and wiring for damage or corrosion.
   
2. Test the sensor for proper functionality and replace if faulty.
   
3. Repair or replace damaged wiring or connectors.
   
4. Clear the fault code and monitor NOx sensor operation and emissions performance.
   
   

How to Avoid It Before It Happens

Prevent this fault by:

• Regularly inspecting the NOx sensor and wiring.
  
• Keeping the SCR system clean and free of contaminants.
  
• Performing routine diagnostics to monitor sensor performance and catch issues early.