SPN 3251 FMI 0 — DPF differential pressure — high (regen required)
Applies to: Detroit · Navistar · Paccar · Sae · Volvo · Universal across brands
DPF differential pressure — high (regen required).
Your SPN/FMI rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- Heavy soot loading
- Sensor lines plugged reading high
- Failed sensor high
- Recent idling patterns
- Heavily-loaded DPF
- Failed sensor reading high
- Plugged lines
First moves (roadside)
- Attempt forced parked regen first
- Then inspect both pressure hoses
- Then verify sensor with key-on ambient reading
- Attempt parked regen
- Inspect pressure hoses
- Check sensor ambient reading
- Forced regen
Common misdiagnoses
- Replacing DPF without attempting regen
FAQ
DPF differential pressure — high (regen required).
Caution — Limp to the next safe stop.
The most common cause is: Heavy soot loading. Other possibilities include Sensor lines plugged reading high; Failed sensor high; Recent idling patterns; Heavily-loaded DPF; Failed sensor reading high; Plugged lines.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.