SPN 27 FMI 5EGRMedium
EGR Valve Position Sensor - Current Below Normal
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Connector Pinout — in guided session
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Overview
Fault Code
SPN 27 / FMI 5
Category
EGR
Severity
Medium
Derate Risk
Sometimes
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR valve position sensor is mounted on the EGR valve assembly, typically located on the intake side of the engine.
Common Symptoms
- EGR valve position sensor current below normal fault active
- Engine derate or power reduction
- Excessive black smoke from exhaust
- Elevated NOx emissions
- DPF regeneration frequency increased
- Rough idle or poor throttle response
- MIL or Check Engine light illuminated
- EGR valve stuck open or closed
Root Causes
- Open circuit in EGR valve position sensor signal or supply wiring
- Corroded or damaged connector at EGR valve assembly
- Failed EGR valve position sensor (internal open)
- Broken or chafed wire between sensor and ECM
- Poor ground connection at EGR valve or ECM
- ECM connector pin damage or moisture intrusion
- Failed EGR valve actuator/sensor assembly
- Blown fuse on sensor supply circuit
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Derate Behavior
Power Derate
Sometimes
Mileage / Regen Notes
SPN 27 FMI 5 typically inhibits or disrupts EGR flow control, which can increase exhaust temperatures and soot load on the DPF, potentially increasing forced regen frequency. Some platforms may inhibit active regen when EGR control is compromised.
System Interactions
SPN 27 FMI 5 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: EGR position 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 27 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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