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Fault Code Reference

SPN 1347 FMI 0AftertreatmentInducement Risk

DPF Differential Pressure - Data Valid But Above Normal

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Overview

Fault Code

SPN 1347 / FMI 0

Category

Aftertreatment

Derate Risk

Yes

Regen Inhibit

No

Inducement Risk

Yes — SCR inducement possible

Component Location: DPF differential pressure sensor is typically mounted on or near the DPF canister on the exhaust aftertreatment system, with two hose ports connecting upstream and downstream of the DPF filter substrate.

Common Symptoms

  • DPF differential pressure reading consistently high
  • Frequent active regenerations requested
  • Check engine light illuminated
  • High exhaust backpressure
  • Loss of engine power or turbo boost
  • Poor fuel economy
  • Black smoke from exhaust during regen attempts
  • Unable to complete regeneration cycles

Root Causes

  • Severely clogged or ash-loaded DPF requiring forced regeneration or physical cleaning
  • Failed or inhibited DPF regeneration allowing excessive soot accumulation
  • Blocked or kinked differential pressure sensor hoses/tubes causing false high reading
  • Faulty differential pressure sensor reporting falsely elevated pressure
  • Exhaust restriction upstream of DPF (collapsed flex pipe, damaged catalyst)
  • Excessive idling or low-load operation preventing passive regeneration
  • DEF/SCR system fault inhibiting regen and allowing soot buildup
  • Oil or coolant contamination of DPF from engine mechanical fault
  • Incorrect DPF installed (wrong part number causing excessive backpressure)

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Derate Behavior

Power Derate

Yes

SCR Inducement Risk

If left unresolved, this fault may trigger SCR inducement — a progressive derate enforced by the ECM to ensure emissions compliance.

Mileage / Regen Notes

SPN 1347 FMI 0 indicates DPF soot or ash load is above normal operational range. Active regeneration may be inhibited or continuously triggered. Prolonged fault can lead to derate conditions (engine power and speed reduction), and in severe cases operator inducement (forced idle or shutdown). Stationary forced regen should be attempted if conditions allow.

System Interactions

SPN 1347 FMI 0 interacts with the following systems and may trigger cascading faults if not resolved promptly.

DPF differential pressure monitoring — soot load calculations affected
SCR NOx conversion efficiency — DEF dosing strategy may be altered
Active regen inhibit logic — regen may be blocked or delayed
Engine protection derate — ECM may reduce power to protect components

Common Diagnostic Mistakes

Replacing the sensor without verifying wiring continuity and supply voltage first.

Clearing codes without identifying and resolving the root cause — the fault will return.

Ignoring related active faults — cascading faults often share a root cause.

Skipping the connector inspection — corrosion and damaged pins are a leading cause of sensor faults.

Condemning the ECM before exhausting all wiring and component tests.

Replacing the DPF without verifying the regen system is functional — a failed regen injector will reload the new DPF.

Ignoring DEF quality — contaminated DEF causes SCR efficiency faults that look like hardware failures.

Deep-dive diagnostic page: SPN 1347 FMI 0 — Full FSM Sequence & Repair Steps — includes wiring notes, sensor specs, and gated repair procedures.

Authority References

Diagnostic procedures on this page are informed by OEM service literature and industry standards.

EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.Cummins QuickServe OnlineOfficial Cummins service manuals, fault code lookup, and TSB database.Detroit Diesel DiagnoCentralDetroit Diesel diagnostic procedures, DDDL documentation, and service literature.PACCAR MX Engine ServicePACCAR MX-11 and MX-13 engine service documentation and DAVIE diagnostic guides.Volvo/Mack Tech ToolVolvo and Mack engine fault code reference and PTT/Tech Tool diagnostic procedures.ASE — Diesel Truck Technician CertificationNational Institute for Automotive Service Excellence — T2 Diesel Engines certification standards.

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