SPN 91 FMI 0Electrical
Accelerator Pedal Position 1 - Data Valid But 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 91 / FMI 0
Category
Electrical
Derate Risk
Yes
Regen Inhibit
No
Inducement Risk
No
Component Location: Accelerator pedal assembly is mounted on the cab floor near the driver's feet, typically bolted to the firewall or floor pan.
Common Symptoms
- Engine RPM increases without pedal input
- Check engine light illuminated
- Throttle response erratic or uncontrolled acceleration
- High idle condition
- Unable to reduce engine speed with pedal release
- ECM records accelerator position higher than actual pedal position
Root Causes
- Accelerator pedal position sensor internal failure Wiring harness short to voltage supply Corroded or damaged connector at accelerator pedal sensor Water or contaminant intrusion in accelerator pedal assembly ECM internal fault reading sensor signal incorrectly
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Derate Behavior
Power Derate
Yes
System Interactions
SPN 91 FMI 0 interacts with the following systems and may trigger cascading faults if not resolved promptly.
ECM communication — J1939 network faults can affect all connected modules
Engine protection — ECM may trigger derate to prevent damage
Aftertreatment — engine protection derates can affect regen strategy
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
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 91 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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