SPN 106 FMI 3Turbo/AirMedium
Air Inlet Pressure — Voltage Above Normal or Shorted High
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 106 / FMI 3
Category
Turbo/Air
Fault Type
sensor
FMI Category
voltage high
Severity
Medium
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Air inlet pressure sensor on air intake duct — between air filter and turbocharger compressor inlet.
Common Symptoms
- Air inlet pressure reading stuck high in live data
- Possible boost monitoring fault
- Engine may run in open-loop boost control
Root Causes
- Air inlet pressure sensor signal wire shorted to voltage
- Sensor internal failure
- Damaged wiring near turbo inlet
- Moisture in sensor connector
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Derate Behavior
Power Derate
No
Mileage / Regen Notes
Low frequency. Random electrical failure.
System Interactions
SPN 106 FMI 3 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: General J1939 sensor diagnosis procedure — SAE J1939-71
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
Cummins
X15: Air inlet pressure sensor monitors turbo inlet vacuum. Used for air filter restriction monitoring.
Detroit
DD15: Confirm sensor location — air inlet vs intake manifold sensors are different components.
PACCAR
MX-13: Check air intake duct for cracks near sensor mounting boss.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 106 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.
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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