SPN 2631 FMI 6EGRMedium
EGR Mass Flow Rate Sensor - 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 2631 / FMI 6
Category
EGR
Severity
Medium
Derate Risk
Sometimes
Regen Inhibit
No
Inducement Risk
No
Component Location: The EGR mass flow sensor is typically located in the EGR cooler outlet pipe between the EGR cooler and intake manifold.
Common Symptoms
- Erratic EGR flow reading
Root Causes
- Short circuit to ground in the EGR mass flow rate sensor signal or supply wiring causing excessive current draw Damaged or chafed wiring harness creating a low-resistance path to ground at the sensor circuit Faulty EGR mass flow rate sensor with internal short causing current above normal Corroded or contaminated connector pins at the EGR mass flow rate sensor harness connector Failed sensor supply voltage regulator within the ECM causing overcurrent condition Moisture or coolant intrusion into the sensor connector causing a short circuit Incorrect sensor installed with mismatched electrical characteristics
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Derate Behavior
Power Derate
Sometimes
Mileage / Regen Notes
Short circuit — inspect wiring before replacing sensor.
System Interactions
SPN 2631 FMI 6 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.
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OEM System Resources
ASE Training Resources
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 2631 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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