SPN 654 FMI 2Medium-High
Injector Cylinder 4 - Data Erratic / Intermittent
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 654 / FMI 2
Severity
Medium-High
Regen Inhibit
No
Inducement Risk
No
Component Location: Valve cover — cylinder 4 injector connector
Common Symptoms
- Misfire on cylinder 4, rough idle, intermittent power loss, smoke
Root Causes
- Injector harness intermittent connection, injector solenoid beginning to fail, ECM injector driver issue
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Derate Behavior
Mileage / Regen Notes
Intermittent — often harness before injector itself; check connector first
System Interactions
SPN 654 FMI 2 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: OEM injector TSBs; Cummins injector harness TSB
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.
OEM Notes
PACCAR
MX-13: Injector trim values in DAVIE; replace if trim >±4 mg/stroke
Cummins
ISX/X15: Check injector harness routing under valve cover; common chafing point at rocker housing
Detroit
DD series: Check injector wiring at valve cover connector; DDDL injector contribution test
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 654 FMI 2 — 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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