SPN 411 FMI 5EGRMedium
EGR Differential Pressure Sensor - Current Below Normal
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DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 411 / FMI 5
Category
EGR
Severity
Medium
Derate Risk
Sometimes
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR differential pressure sensor is typically mounted on or near the EGR cooler or EGR valve assembly on the engine, with pressure ports connected via rubber hoses to the EGR flow passage.
Common Symptoms
- Active fault code SPN 411 FMI 5 stored in ECM
- EGR valve operation may be affected or disabled
- Possible increased NOx emissions
- Engine may exhibit rough idle or poor throttle response
- MIL or Check Engine light illuminated
- Reduced fuel economy
Root Causes
- Open circuit in signal wire between EGR differential pressure sensor and ECM
- Broken or corroded connector pin at sensor harness connector
- Damaged or chafed wiring harness causing open circuit
- Failed EGR differential pressure sensor (internal open)
- Missing or poor ground reference at sensor
- ECM supply voltage wire open causing low current condition
- Connector moisture intrusion causing high resistance
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Derate Behavior
Power Derate
Sometimes
Mileage / Regen Notes
Delta-P sensor open circuit — check wiring before replacing.
System Interactions
SPN 411 FMI 5 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: EGR delta P 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 411 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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