What is SPN 5245 FMI 31 & How to Solve It?

What is SPN 5245 FMI 31:

This is a general warning code, where FMI 31 means abnormal but not defined — usually a catch-all for early warning signs of deeper system issues.

Often triggered by unresolved minor faults or pending emission system problems.

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Why This Happens

• DEF, NOx, or regen faults pending but not active.
• Outdated ECM software.
• Low-quality fuel or DEF.
• Faults suppressed by another system.

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How to Fix It

1. Scan for inactive or pending codes.
2. Resolve any sensor signal delays or mismatches.
3. Update ECM firmware.
4. Run a full regen and emissions system test.
5. Clear code and watch for reappearance.

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How to Avoid It Before It Happens

1. Fix even minor DEF or emissions faults quickly.
2. Keep ECMs and modules fully updated.
3. Use only high-quality consumables.