SPN 412 FMI 11EGR
EGR Temperature - Root Cause Not Known
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Overview
Fault Code
SPN 412 / FMI 11
Category
EGR
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR temperature sensor is mounted on the EGR cooler outlet or EGR mixer/intake manifold connection, typically on the passenger or driver side of the engine near the EGR cooler assembly.
Common Symptoms
- Check engine light illuminated
- Engine derate or power loss
- Increased exhaust smoke
- Poor fuel economy
- EGR system fault codes present
Root Causes
- Intermittent or erratic signal from EGR temperature sensor due to loose or corroded connector EGR temperature sensor internal failure producing inconsistent or irrational readings Wiring harness chafing or intermittent open circuit in EGR temperature sensor circuit EGR cooler partial blockage or fouling causing abnormal temperature behavior ECM unable to rationalize EGR temperature against other sensor inputs (MAP, IAT, coolant temp) EGR valve stuck open or partially open causing unexpected temperature readings Exhaust gas recirculation cooler failure allowing coolant intrusion and erratic temps Software or calibration issue causing rationality fault with no clear electrical failure Multiple intermittent faults confusing ECM diagnostic strategy, triggering FMI 11
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Derate Behavior
Power Derate
No
Mileage / Regen Notes
SPN 412 FMI 11 may inhibit or delay active DPF regeneration because the ECM cannot confirm reliable EGR temperature data needed to validate exhaust thermal conditions. Regen inhibit or derate conditions are likely active when this fault is present, depending on OEM calibration.
System Interactions
SPN 412 FMI 11 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.
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 11 — 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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