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SPN 520371 FMI 31Severity: Warning

SPN 520371 FMI 31: DPF regeneration inhibited due to conditions – regen will not initiate

Quick Answer

DPF regeneration inhibited due to conditions – regen will not initiate

Code
SPN 520371 FMI 31
Severity
Warning
Applies to
Check OEM application
Can I drive?
Driving suitability is not established by this code alone.

Common Symptoms

  • Regen requested but will not start
  • Soot % increases over time
  • Eventually leads to derate if ignored

Likely Causes

  • Low exhaust temp (short trips, lots of idle)
  • Vehicle not meeting regen conditions
  • Other active faults blocking regen

Common Fixes

  • Meet regen conditions and allow full regen
  • Fix any active aftertreatment sensor faults
  • Reduce excessive idle and short-trip cycles
Full technical sections↓

What does SPN 520371 FMI 31 mean?

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DPF regeneration inhibited due to conditions – regen will not initiate

Detailed guide for SPN 520371 FMI 31

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This shows up when the system wants to regen but refuses to start because conditions are not right.\n\nIf you keep driving like nothing is happening, soot climbs until you get a real restriction/derate code.

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