SPN 2031 FMI 0Exhaust
Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 2031 / FMI 0
Category
Exhaust
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: Bank 1 Sensor 1 EGT sensor is typically located in the exhaust manifold or upstream turbocharger inlet on the number one cylinder bank side.
Common Symptoms
- Exhaust temperature reading abnormally high on scan tool
- DEF dosing reduced or stopped
- SCR efficiency monitor fault may trigger
- DPF regeneration may not complete properly
- Check engine light illuminated
- Possible white smoke from excessive DEF injection
Root Causes
- Faulty exhaust gas temperature sensor Damaged or corroded wiring harness to EGT sensor Moisture intrusion in sensor connector Sensor connector pins pushed back or loose ECM internal fault
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Derate Behavior
Power Derate
No
System Interactions
SPN 2031 FMI 0 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.
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OEM System Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 2031 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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