SPN 2659 FMI 0EGR SystemHigh
EGR Mass Flow Rate — Data Valid But Above Normal (Most Severe)
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DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 2659 / FMI 0
Category
EGR System
Fault Type
sensor
FMI Category
above normal
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR valve on exhaust manifold or EGR cooler outlet — typically driver side of engine. EGR mass flow sensor in EGR passage.
Common Symptoms
- EGR flow reading above maximum in live data
- Engine derate or EGR system fault active
- Possible black smoke under load
- EGR valve stuck open or over-commanded
- Intake manifold pressure lower than expected
Root Causes
- EGR valve stuck open — carbon buildup or actuator failure
- EGR mass flow sensor failure reading high
- EGR cooler bypass valve stuck open
- ECM EGR command fault — over-commanding EGR flow
- EGR differential pressure sensor fault
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
EGR valve carbon buildup increases with mileage. Higher frequency in high-idle applications.
System Interactions
SPN 2659 FMI 0 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: Cummins TSB 4021889 — EGR System Diagnosis and Valve Cleaning Procedure
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 valve carbon buildup is primary cause. INSITE EGR valve test required for diagnosis.
Detroit
DD15: EGR valve cleaning procedure in DDDL. High-mileage DD15 engines commonly develop EGR valve sticking.
PACCAR
MX-13: EGR valve replacement common at 400k+ miles. Carbon buildup accelerated by high idle time.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 2659 FMI 0 — 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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