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Fault Code Reference

SPN 3510 FMI 0AftertreatmentMedium

DEF Pressure Sensor - High

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Overview

Fault Code

SPN 3510 / FMI 0

Category

Aftertreatment

Severity

Medium

Derate Risk

Sometimes

Regen Inhibit

No

Inducement Risk

No

Component Location: DEF pressure sensor is mounted on or near the DEF pump assembly, typically located on frame rail near DEF tank.

Common Symptoms

  • High DEF pressure reading on scan tool (above 120 psi). MIL/CEL illuminated. DEF warning lamp on. Possible white exhaust smoke if DEF is over-dosing. Poor DEF spray pattern at injector. Frozen or slow-responding DEF gauge. Customer may report reduced power if derate is active. DEF fluid leaking from pressure relief areas in severe cases.

Root Causes

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Derate Behavior

Power Derate

Sometimes

Mileage / Regen Notes

This fault typically does not directly inhibit active DPF regeneration. However, if DEF dosing is affected by the high pressure condition, SCR efficiency may drop, potentially causing elevated NOx codes that CAN inhibit regen. Monitor SCR inlet/outlet NOx readings during diagnosis. If DEF dosing is erratic due to pressure issues, the system may reduce or stop dosing which could trigger SCR-related regen lockouts on some platforms.

System Interactions

SPN 3510 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
TSB Reference: No confirmed TSBs — verify in OEM service portal. Check for manufacturer-specific bulletins related to DEF return line routing, DEF crystallization issues, and pressure sensor calibration updates. Cummins ISB/ISX platforms may have service letters regarding DEF line freeze damage. Detroit DD13/DD15 may have bulletins on DEF tank return fitting crystallization.

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 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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