SPN 1807 FMI 13Driveline
Transmission Output Shaft Speed - Out of Calibration
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DVOM Testing — in guided session
Connector Pinout — in guided session
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Overview
Fault Code
SPN 1807 / FMI 13
Category
Driveline
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: The transmission output shaft speed sensor is typically mounted on the transmission tail housing near the output shaft.
Common Symptoms
- Speedometer reading erratic or inaccurate
- Transmission shifting harshly or at incorrect speeds
- Cruise control not engaging or dropping out unexpectedly
- ABS or traction control warning lights active
- Vehicle speed displayed incorrectly on dash
Root Causes
- Output shaft speed sensor calibration drift Faulty transmission output speed sensor Damaged tone ring or reluctor wheel on output shaft Incorrect tire size or final drive ratio programmed in ECU Wiring harness damage or corrosion at sensor connector
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Derate Behavior
Power Derate
No
System Interactions
SPN 1807 FMI 13 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
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Related Diagnostic Articles
Deep-dive diagnostic page: SPN 1807 FMI 13 — 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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