SPN 2791 FMI 6EGRMedium
EGR Valve - Current Above Normal
Scan Tool — in guided session
DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 2791 / FMI 6
Category
EGR
Severity
Medium
Derate Risk
Sometimes
Regen Inhibit
No
Inducement Risk
No
Component Location: The EGR valve is typically mounted on the intake manifold or near the engine air intake system.
Common Symptoms
- EGR valve not responding or stuck in position. Check engine light illuminated. Poor engine performance or rough idle. Black smoke from exhaust due to improper EGR flow. Engine may run rich. Possible elevated NOx emissions. EGR system may default to closed position. Intermittent power loss during acceleration. May notice EGR valve cycling erratically or buzzing sound from actuator.
Root Causes
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Derate Behavior
Power Derate
Sometimes
Mileage / Regen Notes
This fault typically does not directly inhibit active DPF regeneration. However, if the EGR valve is stuck or not functioning, exhaust gas temperatures and engine-out emissions may be affected, which can indirectly impact regen efficiency. If combined with other EGR or aftertreatment faults, active regen may be inhibited. Verify no regen inhibit flags are set in scan tool before attempting regen.
System Interactions
SPN 2791 FMI 6 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: No confirmed universal TSBs — verify in OEM service portal. Cummins ISX and ISB engines have had documented EGR valve harness chafing issues near firewall pass-through. Detroit DD13/DD15 have had connector corrosion concerns. Check OEM QuickServe, DTNA ServicePro, or applicable portal for model-specific bulletins.
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 2791 FMI 6 — 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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