SPN 3610 FMI 4TurbochargerHigh
Turbocharger Wastegate Actuator — Voltage Below Normal or Open Circuit
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Connector Pinout — in guided session
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Overview
Fault Code
SPN 3610 / FMI 4
Category
Turbocharger
Fault Type
actuator
FMI Category
voltage low
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: Wastegate actuator mounted on turbocharger — typically passenger side of engine.
Common Symptoms
- Wastegate actuator not responding to commands
- Boost pressure uncontrolled — over-boost or under-boost
- Engine derate under load
- Wastegate position feedback reading low or zero
Root Causes
- Wastegate actuator power supply open circuit
- Wastegate actuator wiring — open circuit or short to ground
- Wastegate actuator motor failure — open circuit
- Wastegate actuator connector damaged or disconnected
- ECM actuator driver fault
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
Wiring failure common at 300k+ miles due to heat cycling near turbocharger.
System Interactions
SPN 3610 FMI 4 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
TSB Reference: Cummins TSB 4021834 — Wastegate Actuator Diagnosis and Replacement
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: Confirm engine has wastegate vs VGT before diagnosis. Wastegate actuator wiring harness routes near exhaust — check for heat damage.
Detroit
DD15: Uses VGT, not wastegate. SPN 3610 on DD platform may refer to different actuator.
PACCAR
MX-13: Inspect actuator wiring harness routing — known chafe point near turbo heat shield.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 3610 FMI 4 — 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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