SPN 243 FMI 0Turbocharger
Turbocharger/Supercharger Wastegate Control A Low
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 243 / FMI 0
Category
Turbocharger
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Wastegate actuator is mounted on the turbocharger housing with the control solenoid typically located nearby on the engine block or intake manifold.
Common Symptoms
- Engine derate or power loss
- Excessive turbo boost pressure
- Turbo overboost condition
- Check engine light illuminated
- Reduced fuel economy
- Audible turbo surge or flutter
- Black smoke from exhaust under load
Root Causes
- Wastegate actuator mechanical failure or seized linkage Faulty wastegate control solenoid valve Vacuum or air supply leak to wastegate actuator Damaged or disconnected wastegate control hoses Corroded or damaged wiring to wastegate control solenoid
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Derate Behavior
Power Derate
No
System Interactions
SPN 243 FMI 0 interacts with the following systems and may trigger cascading faults if not resolved promptly.
Boost pressure — engine air/fuel ratio and power output affected
EGR system — boost pressure affects EGR flow calculations
Aftertreatment — low boost can cause incomplete combustion and DPF loading
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 243 FMI 0 — 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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