SPN 1351 FMI 7Fuel SystemHigh
Fuel Injector Cylinder 5 — Mechanical System Not Responding
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Connector Pinout — in guided session
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Overview
Fault Code
SPN 1351 / FMI 7
Category
Fuel System
Fault Type
actuator
FMI Category
mechanical
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: Cylinder 5 injector — fifth from front of engine. Valve cover removal required.
Common Symptoms
- Rough idle — cylinder 5 misfire
- Engine vibration
- Black or white smoke
- Low power
- Cylinder 5 contribution test shows low output
Root Causes
- Injector solenoid failure
- Injector mechanical failure
- ECM driver circuit fault
- Wiring harness fault
- Contaminated fuel
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
High frequency at 400k–700k miles.
System Interactions
SPN 1351 FMI 7 interacts with the following systems and may trigger cascading faults if not resolved promptly.
Fuel rail pressure — injector timing and quantity affected
Engine power output — derate may be triggered to protect injectors
Aftertreatment regen — low fuel pressure can prevent regen completion
TSB Reference: Cummins TSB 4021923 — Injector Diagnosis, Removal, and Replacement Procedure
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 injectors without verifying fuel supply pressure — low supply pressure causes injector faults.
Ignoring fuel filter restriction — a clogged filter causes low rail pressure that mimics injector failure.
OEM Notes
Cummins
X15: Injector trim code programming required. Use INSITE.
Detroit
DD15: IQA programming required. Use DDDL.
PACCAR
MX-13: IQA coding required. Use DAVIE or PACCAR ESA.
Related Faults in This Category
OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 1351 FMI 7 — 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.
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.EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.
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