What are the most likely causes of SPN 3251 FMI 0?

Soot loading from short trips without a complete regen; Differential pressure sensor hoses plugged with soot; Differential pressure sensor out of calibration

How do you diagnose code SPN 3251 FMI 0?

1) Read DPF differential pressure at idle with the scanner — Under 1 kPa at warm idle 2) Inspect the pressure sensor hoses — Clean hoses, no soot and no kinks 3) Attempt a full parked regeneration — Regen completes and pressure drops

What part is usually replaced for SPN 3251 FMI 0 and how much does it cost?

DPF differential pressure sensor: $180–$420 USD (aftermarket to dealer), plus 1–2 h of labor.

← All codes

SPN 3251 FMI 0

CAUTION

Particulate filter

The particulate filter is plugged and the engine is losing power.

SPN 3251 FMI 0: The particulate filter is plugged and the engine is losing power. Caution: you can keep driving carefully, but the engine may derate; get it addressed soon.

Mechanical · Aftertreatment / DPF

Can I keep driving?

Caution: you can keep driving carefully, but the engine may derate; get it addressed soon.

What it means

DPF differential pressure went above its limit. Soot did not burn off during normal regeneration, usually from short trips, a mis-reading pressure sensor, or plugged pressure hoses. Left alone, the engine will enter a torque and speed derate.

Most likely causes

Soot loading from short trips without a complete regen
Very likely
Differential pressure sensor hoses plugged with soot
Likely
Differential pressure sensor out of calibration
Likely
Ash-loaded DPF at end of service life
Less likely

Tests, cheapest and most decisive first

1. Read DPF differential pressure at idle with the scanner
Expected result: Under 1 kPa at warm idle
Tool: J1939 scanner
2. Inspect the pressure sensor hoses
Expected result: Clean hoses, no soot and no kinks
3. Attempt a full parked regeneration
Expected result: Regen completes and pressure drops
Tool: J1939 scanner