Home › Codes › SPN 3251 › FMI 15

SPN 3251 FMI 15

Aftertreatment 1 DPF Differential Pressure — Value too high (least severe).
The reading is above normal, but only at the lowest warning level.

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 15 usually points to: An early warning: mild over-temperature or over-pressure, or a sensor starting to drift high. More on FMI 15.

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 15 mean?

Aftertreatment 1 DPF Differential Pressure — value too high (least severe). The reading is above normal, but only at the lowest warning level.

Is SPN 3251 FMI 15 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 15?

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).