SPN 412 FMI 1EGRHigh
EGR Temperature — Low (EGR Cooler Efficiency)
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DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 412 / FMI 1
Category
EGR
Fault Type
sensor
FMI Category
performance
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR cooler — typically on engine block, connected between exhaust manifold and EGR valve
Common Symptoms
- EGR cooler efficiency fault
- EGR temperature not dropping as expected
- Possible derate
- Increased NOx emissions
Root Causes
- EGR cooler plugged with soot
- EGR cooler internal leak (coolant into exhaust)
- EGR cooler bypass valve stuck
- EGR temp sensor failed
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
EGR cooler failure common at 300k–500k miles. Internal leaks accelerated by thermal cycling.
System Interactions
SPN 412 FMI 1 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: Cummins TSB 4021330 — EGR Cooler Efficiency Diagnosis; Detroit TSB 18-037 — EGR Cooler 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: EGR cooler internal leak causes white smoke and coolant loss.
Detroit
DD15: EGR cooler failure common at 300k–500k miles. Check coolant level daily.
PACCAR
MX-13: EGR cooler cleaning service available before replacement.
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OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 412 FMI 1 — 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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