SPN 102 FMI 1Turbo/AirHigh
Engine Intake Manifold Pressure — Low
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 102 / FMI 1
Category
Turbo/Air
Fault Type
sensor
FMI Category
performance
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: Turbocharger — exhaust manifold mounted; CAC — front of truck behind grille
Common Symptoms
- Low boost pressure
- Black smoke under load
- Reduced power
- Turbo lag
- Poor fuel economy
Root Causes
- Turbocharger worn or damaged
- Charge air cooler (CAC) leak
- Intake air leak downstream of turbo
- EGR system malfunction
- Air filter restriction
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
Turbo wear common at 400k–600k miles. CAC leaks common at 200k–400k miles.
System Interactions
SPN 102 FMI 1 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: Cummins TSB 4021550 — Low Boost Pressure Diagnosis; Detroit TSB 18-025 — Turbocharger Diagnosis
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: VGT turbo — check vane position actuator. INSITE shows vane position %.
Detroit
DD15: Check EGR cooler for leaks contributing to low boost.
PACCAR
MX-13: CAC leak common at charge air cooler end tanks. Pressure test required.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 102 FMI 1 — 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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