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SPN 3251 FMI 16

Aftertreatment 1 DPF Differential Pressure — Value too high (moderately severe).
The reading is above normal at a middle warning level — more serious than FMI 15, less than FMI 0.

What the SPN covers: Pressure difference across the diesel particulate filter — how hard the exhaust is working to push through it. More on SPN 3251.

What FMI 16 usually points to: A developing over-condition that often precedes a derate. More on FMI 16.

Severity

MEDIUM — fix soon

High readings mean a loaded or plugged DPF. Regenerate or service soon to avoid a severe derate.

Likely causes

  1. DPF loaded with soot or ash
  2. Cracked or melted sensor hoses/tubes
  3. Faulty differential pressure sensor
  4. Failed regeneration due to other faults

Checks & fixes (easiest first)

  1. Inspect the sensor tubes for cracks, plugging or reversed lines
  2. Read soot load and perform a parked regen if allowed
  3. Check the sensor key-on, engine-off reading (should be near zero)
  4. Have the DPF cleaned or replaced if ash-loaded

FAQ

What does SPN 3251 FMI 16 mean?

Aftertreatment 1 DPF Differential Pressure — value too high (moderately severe). The reading is above normal at a middle warning level — more serious than FMI 15, less than FMI 0.

Is SPN 3251 FMI 16 serious?

High readings mean a loaded or plugged DPF. Regenerate or service soon to avoid a severe derate.

What should I check first for SPN 3251 FMI 16?

Inspect the sensor tubes for cracks, plugging or reversed lines; Read soot load and perform a parked regen if allowed; Check the sensor key-on, engine-off reading (should be near zero).