SPN 107 FMI 2Engine Protection
Air Filter Differential Pressure - 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 107 / FMI 2
Category
Engine Protection
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Air filter differential pressure sensor is typically mounted on or near the air filter housing on the intake system.
Common Symptoms
- Intermittent or fluctuating air filter restriction warning
- Erratic boost pressure readings
- Check engine light illuminated intermittently
- Unstable engine performance or power fluctuations
- Air filter restriction gauge reading erratic
Root Causes
- Clogged or restricted air filter element Faulty differential pressure sensor or loose connections Air intake system leaks or cracked ducting Water or debris in differential pressure sensor lines Intermittent wiring harness issues to the differential pressure sensor
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Derate Behavior
Power Derate
No
System Interactions
SPN 107 FMI 2 interacts with the following systems and may trigger cascading faults if not resolved promptly.
ECM communication — J1939 network faults can affect all connected modules
Engine protection — ECM may trigger derate to prevent damage
Aftertreatment — engine protection derates can affect regen strategy
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.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 107 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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