SPN 412 FMI 5EGRMedium
EGR Temperature Sensor - Current Below Normal
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 412 / FMI 5
Category
EGR
Severity
Medium
Derate Risk
Sometimes
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR temperature sensor is typically mounted on the EGR cooler outlet or EGR mixer pipe on the intake side of the engine, near the EGR valve assembly.
Common Symptoms
- EGR temperature sensor fault code active
- Engine may exhibit reduced performance or derate
- Possible failed or inhibited DPF regeneration
- EGR valve operation may be limited or disabled
- MIL or Check Engine light illuminated
- Abnormal or implausible EGR temperature readings in diagnostics
Root Causes
- Open circuit in EGR temperature sensor signal or supply wiring
- Corroded or damaged sensor connector pins
- Faulty or failed EGR temperature sensor
- Broken or chafed wiring harness between sensor and ECM
- Poor ground connection at sensor or ECM
- Connector pin pushed back or spread causing high resistance
- ECM hardware failure (rare)
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Derate Behavior
Power Derate
Sometimes
Mileage / Regen Notes
DPF regeneration may be inhibited or disabled when EGR temperature sensor reports current below normal (open circuit). ECM cannot accurately manage EGR flow or exhaust temperatures, preventing safe regen initiation.
System Interactions
SPN 412 FMI 5 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: EGR temp TSB
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 412 FMI 5 — 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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