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Fault Code Reference

SPN 2002 FMI 0AftertreatmentInducement Risk

DPF Efficiency Below Threshold

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Overview

Fault Code

SPN 2002 / FMI 0

Category

Aftertreatment

Derate Risk

Yes

Regen Inhibit

No

Inducement Risk

Yes — SCR inducement possible

Component Location: DPF (Diesel Particulate Filter) is mounted in the exhaust aftertreatment system downstream of the DOC, typically mid-chassis or under-cab on the frame rail or in a vertical/horizontal aftertreatment canister.

Common Symptoms

  • DPF differential pressure higher than expected during regen cycle
  • Active DPF regeneration occurring more frequently than normal
  • Reduced fuel economy due to excessive regen events
  • MIL or aftertreatment warning lamp illuminated
  • White or gray exhaust smoke during or after regen attempt
  • Possible derate or power reduction if fault becomes active

Root Causes

  • DPF substrate cracked, melted, or physically damaged reducing filtration efficiency
  • DPF substrate clogged beyond recoverable ash loading requiring replacement
  • Incomplete or failed active/passive regeneration cycles allowing excessive soot accumulation
  • Oil consumption causing accelerated ash accumulation in DPF substrate
  • Upstream DOC degraded or failed, reducing NO2 available for passive regen
  • Incorrect fuel or lube oil specification accelerating ash and soot loading
  • Exhaust leaks upstream of DPF differential pressure sensors causing false readings
  • DPF differential pressure sensor tubes blocked, cracked, or disconnected
  • Faulty upstream or downstream exhaust temperature sensor skewing efficiency calculation
  • Extended idle operation or low-load duty cycle inhibiting passive regeneration
  • EGR system malfunction causing excessive soot production
  • Injector imbalance or late post-injection causing incomplete combustion and soot increase

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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 2002 FMI 0 indicates DPF filtration efficiency has dropped below the ECM threshold. Active and passive regenerations are typically inhibited or disabled when this fault is active, as the ECM determines the DPF substrate can no longer adequately trap particulates. A forced parked regen may be locked out pending diagnosis. Vehicle may enter derate or limp mode depending on OEM strategy.

System Interactions

SPN 2002 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 2002 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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