What is SPN 5298 & How to Solve It?

What is SPN 5298:

SPN 5298 indicates a fault related to the Aftertreatment Diesel Exhaust Fluid (DEF) System Monitoring. This code is triggered when the control module detects that the system has not properly completed DEF-related tests over a set period. It’s often tied to conditions preventing the onboard diagnostics (OBD) system from confirming correct DEF operation—such as frequent power interruptions, failed sensor tests, or incomplete regeneration cycles.

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Why This Happens

• Incomplete or failed DEF system diagnostics.
  
• Power loss to the aftertreatment control module.
  
• Frequent ignition cycles interrupting system monitoring.
  
• Faults in related components (e.g., NOx sensor, DEF level sensor).
  
• Software or calibration mismatch preventing test completion.
  
  

How to Fix It

1. Check for any active or stored faults in the DEF and emissions system.
   
2. Perform a full regeneration cycle to reset monitoring conditions.
   
3. Inspect the NOx sensors and DEF sensors for accuracy and operation.
   
4. Ensure no power interruptions are occurring during system tests.
   
5. Update the ECM or aftertreatment module software if required.
   
   

How to Avoid It Before It Happens

• Allow the vehicle to complete full drive and regen cycles without interruption.
  
• Regularly scan for emission-related fault codes.
  
• Keep battery and ignition systems stable and well-maintained.
  
• Ensure all software and calibrations are current.
  
• Perform routine DEF system checks during scheduled service intervals.
• Use Clue’s Preventive Maintenance to ensure regular DEF system checks, allowing for smooth regeneration cycles and stable system performance.