SPN 1323 FMI 7Turbo
Turbocharger Compressor Outlet Pressure - Mechanical System Not Responding
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Connector Pinout — in guided session
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Overview
Fault Code
SPN 1323 / FMI 7
Category
Turbo
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: The turbocharger compressor outlet pressure sensor is mounted on the intake side of the turbocharger or in the charged air system downstream of the compressor.
Common Symptoms
- Engine derate or reduced power output
- Check engine light illuminated
- Poor throttle response or turbo lag
- Black smoke under heavy acceleration
- Turbocharger boost pressure lower than expected
Root Causes
- Turbocharger wastegate actuator stuck or binding Wastegate control valve malfunction Turbocharger VGT mechanism seized or restricted Boost control solenoid failure Exhaust restriction or clogged DPF affecting turbo operation
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Derate Behavior
Power Derate
Yes
System Interactions
SPN 1323 FMI 7 interacts with the following systems and may trigger cascading faults if not resolved promptly.
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 1323 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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