SPN 3227 FMI 5AftertreatmentInducement Risk
Aftertreatment 1 Fuel Pressure Control Actuator - Current Below Normal or Open Circuit
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Overview
Fault Code
SPN 3227 / FMI 5
Category
Aftertreatment
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
Yes — SCR inducement possible
Component Location: Aftertreatment fuel pressure control actuator (solenoid) is located in the aftertreatment fuel supply circuit, typically mounted near the diesel burner/doser unit on or near the DPF assembly under the vehicle or on the frame rail.
Common Symptoms
- Check engine light illuminated
- DPF regeneration fails to initiate
- Aftertreatment system derate
- Dosing fuel injector not operating
- Regeneration incomplete warning
Root Causes
- Open circuit in the fuel pressure control actuator wiring harness Failed or burned-out aftertreatment fuel pressure control actuator (solenoid) coil Corroded, damaged, or pushed-back terminals at the actuator connector Broken or chafed wire between ACM and actuator Blown fuse supplying the actuator circuit Poor ground connection at the ACM or actuator ground return circuit Failed ACM output driver (less common)
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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
FMI 5 on the aftertreatment fuel pressure control actuator will typically inhibit active DPF regeneration since the system cannot properly control diesel fuel delivery to the burner/doser. Parked and forced regen will be disabled. A high soot load condition may develop if the fault persists. Some platforms may also illuminate a DPF warning lamp and restrict vehicle operation if soot accumulation reaches critical levels.
System Interactions
SPN 3227 FMI 5 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 3227 FMI 5 — 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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