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Fault Code Reference

SPN 3700 FMI 16AftertreatmentInducement Risk

Aftertreatment Fuel Pressure - Data Valid But Above Normal

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Overview

Fault Code

SPN 3700 / FMI 16

Category

Aftertreatment

Derate Risk

Yes

Regen Inhibit

No

Inducement Risk

Yes — SCR inducement possible

Component Location: Aftertreatment fuel pressure sensor is mounted on the doser fuel supply circuit, typically near the aftertreatment fuel pump module on the frame rail or DPF assembly.

Common Symptoms

  • Aftertreatment fuel pressure reading consistently above normal operating range
  • DPF regeneration may be inhibited or incomplete
  • Check engine light illuminated with amber warning
  • Dosing system may limit DEF injection
  • Possible fuel odor from aftertreatment system
  • Excessive fuel consumption during regen attempts

Root Causes

  • Restricted or clogged aftertreatment fuel injector (doser injector) causing pressure buildup Faulty aftertreatment fuel pressure sensor providing erroneous high reading Plugged aftertreatment fuel supply line or filter screen restricting flow and causing pressure spike Aftertreatment fuel pump relief valve stuck closed or faulty, allowing excessive pressure Return line restriction or kink causing elevated backpressure in the doser fuel circuit ACM software or calibration issue causing incorrect pressure threshold interpretation

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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 3700 FMI 16 will inhibit active DPF regeneration. The ACM will block regen commands to prevent doser operation under abnormal fuel pressure conditions, potentially leading to elevated soot load and a parked regen requirement once the fault is resolved.

System Interactions

SPN 3700 FMI 16 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 3700 FMI 16 — 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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