SPN 27 FMI 3EGRHigh
EGR Valve Position — Voltage 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 27 / FMI 3
Category
EGR
Fault Type
sensor
FMI Category
voltage high
Severity
High
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: EGR valve position sensor — integrated with EGR valve assembly, typically on intake manifold
Common Symptoms
- EGR valve position sensor reading high
- Engine derate
- Increased NOx emissions
- EGR system not controlling properly
Root Causes
- EGR position sensor shorted high
- 5V reference shorted to battery
- Sensor connector damage
- ECM input circuit fault
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Derate Behavior
Power Derate
Yes
Mileage / Regen Notes
EGR valve carbon buildup common at 150k–300k miles. Sensor failure at 200k–400k miles.
System Interactions
SPN 27 FMI 3 interacts with the following systems and may trigger cascading faults if not resolved promptly.
TSB Reference: Cummins TSB 4021300 — EGR Valve Position Sensor Diagnosis; Detroit TSB 18-035 — EGR System Diagnosis
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 and position sensor are one assembly. Carbon buildup common.
Detroit
DD15: DDDL shows EGR valve position %. Check for carbon buildup before condemning sensor.
PACCAR
MX-13: EGR valve cleaning service available. Check before replacement.
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OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 27 FMI 3 — 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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