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Fault Code Reference

SPN 3510 FMI 31AftertreatmentInducement Risk

Aftertreatment 1 Diesel Exhaust Fluid Doser Absolute Pressure - Condition Exists

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Overview

Fault Code

SPN 3510 / FMI 31

Category

Aftertreatment

Derate Risk

Yes

Regen Inhibit

No

Inducement Risk

Yes — SCR inducement possible

Component Location: DEF doser is mounted on the decomposition tube or inlet to the SCR catalyst in the exhaust aftertreatment system.

Common Symptoms

  • DEF system malfunction lamp illuminated
  • DEF pump running excessively or continuously
  • Poor NOx conversion efficiency
  • DEF consumption higher than normal
  • SCR inducement warning or countdown timer active
  • White smoke from exhaust during DEF dosing
  • Check engine light with aftertreatment fault

Root Causes

  • DEF doser valve clogged or crystallized with urea deposits DEF supply line restricted or kinked upstream of doser DEF pump assembly failing or not building adequate pressure DEF strainer/filter plugged restricting flow to doser DEF quality issue - diluted or contaminated DEF reducing pump efficiency DEF doser absolute pressure sensor failed or out of calibration Air ingestion in DEF supply line causing pressure irregularity DEF tank level critically low causing pump cavitation Wiring or connector fault at DEF doser pressure sensor circuit ACM software or calibration issue misinterpreting pressure signal

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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

Active DPF regeneration will be inhibited or limited when DEF doser pressure faults are present, as the SCR system cannot confirm proper DEF injection. Passive regen may still occur. Prolonged fault condition can lead to SCR efficiency derate and potential vehicle speed or torque derate depending on OEM strategy.

System Interactions

SPN 3510 FMI 31 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 3510 FMI 31 — 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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