SPN 3610 FMI 3Aftertreatment
Aftertreatment Fuel Pressure 2 - Voltage Above Normal or Shorted High
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Overview
Fault Code
SPN 3610 / FMI 3
Category
Aftertreatment
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Aftertreatment fuel pressure sensor 2 is mounted on the aftertreatment fuel supply line or doser fuel rail, typically near the DPF/DOC assembly on the exhaust aftertreatment system.
Common Symptoms
- Aftertreatment fuel pressure sensor reading abnormally high or max value
- Diesel exhaust fluid dosing malfunction or inhibited
- Parked or stationary regeneration may fail or be inhibited
- Check engine light or MIL illuminated
- DPF regeneration incomplete or unsuccessful
Root Causes
- Fuel pressure sensor 2 signal wire shorted to voltage source (5V reference or battery voltage) Failed or internally shorted aftertreatment fuel pressure sensor 2 Damaged or chafed wiring harness causing short to power on signal circuit Corroded or contaminated sensor connector causing high resistance or cross-circuit fault Failed ACM (Aftertreatment Control Module) with internal short on sensor input circuit Incorrect sensor installed (wrong reference voltage range)
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Derate Behavior
Power Derate
No
Mileage / Regen Notes
An active SPN 3610 FMI 3 fault will typically inhibit active DPF regeneration as the ACM cannot accurately determine aftertreatment fuel pressure, preventing safe doser operation. Parked and forced regen will be disabled while the fault is active.
System Interactions
SPN 3610 FMI 3 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.
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OEM System Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 3610 FMI 3 — 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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