What is SPN 3363 FMI 5 & How to Solve It?

What is SPN 3363 FMI 5:

SPN 3363 FMI 5 indicates a fault with the Aftertreatment 1 Diesel Exhaust Fluid (DEF) Dosing Valve Circuit – Electrical Current Below Normal or Open. This means the engine control module (ECM) has detected that the current in the DEF dosing valve circuit is lower than expected or the circuit is open, potentially affecting DEF injection and emissions control.

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Why This Happens

Common causes include:

• Faulty or damaged DEF dosing valve.
  
• Open or damaged wiring in the dosing valve circuit.
  
• Corroded or loose connectors.
  
• Faulty ECM or sensor calibration problems.
  
  

How to Fix It

To resolve this fault:

1. Inspect the DEF dosing valve and wiring for damage or corrosion.
   
2. Test the valve’s electrical current and replace if faulty.
   
3. Repair or replace damaged wiring or connectors.
   
4. Clear the fault code and verify DEF injection system operation.
   
   

How to Avoid It Before It Happens

Prevent this fault by:

• Regularly inspecting the DEF dosing valve and wiring.
  
• Maintaining clean and secure electrical connections.
  
• Performing routine diagnostics to catch issues early.
• Implement Clue’s Preventive Maintenance to regularly inspect the DEF dosing valve and wiring, ensuring they remain in optimal working condition.