SPN 3058 FMI 3AftertreatmentInducement Risk
Aftertreatment 1 Outlet Gas Sensor - Voltage Above Normal
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Overview
Fault Code
SPN 3058 / FMI 3
Category
Aftertreatment
Derate Risk
Possible
Regen Inhibit
No
Inducement Risk
Yes — SCR inducement possible
Component Location: The Aftertreatment Outlet NOx sensor is located downstream of the SCR catalyst in the exhaust system.
Common Symptoms
- Check engine light illuminated
- NOx sensor reading stuck high or implausible
- SCR efficiency fault codes present
- DEF dosing system may command excessive DEF injection
- Aftertreatment outlet NOx reading shows constant high voltage
- SCR catalyst efficiency monitoring disabled
Root Causes
- Open circuit in the signal wire between the aftertreatment outlet gas sensor and ACM Sensor signal wire shorted to voltage (B+) Failed or damaged aftertreatment 1 outlet NOx/temperature/O2 sensor (depending on platform) Corroded or spread connector pins at the sensor harness connector Damaged wiring harness routed near hot exhaust components causing insulation failure Failed ACM (rare, only after all wiring and sensor confirmed good)
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Derate Behavior
Power Derate
Possible
SCR Inducement Risk
If left unresolved, this fault may trigger SCR inducement — a progressive derate enforced by the ECM to ensure emissions compliance.
System Interactions
SPN 3058 FMI 3 interacts with the following systems and may trigger cascading faults if not resolved promptly.
DPF differential pressure monitoring — soot load calculations affected
SCR NOx conversion efficiency — DEF dosing strategy may be altered
Active regen inhibit logic — regen may be blocked or delayed
Engine protection derate — ECM may reduce power to protect components
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.
Replacing the DPF without verifying the regen system is functional — a failed regen injector will reload the new DPF.
Ignoring DEF quality — contaminated DEF causes SCR efficiency faults that look like hardware failures.
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OEM System Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 3058 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.
EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx 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.
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