SPN 1241 FMI 7ABS
Wheel Speed Sensor - Right Front - Mechanical System Not Responding
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Overview
Fault Code
SPN 1241 / FMI 7
Category
ABS
Derate Risk
No
Regen Inhibit
No
Inducement Risk
No
Component Location: The right front wheel speed sensor is mounted at the right front wheel hub assembly near the brake components.
Common Symptoms
- ABS warning lamp illuminated on dash
- ABS system disabled or inactive
- Traction control system fault
- Stability control warning light active
- Vehicle may pull to one side during braking
Root Causes
- Damaged or broken wheel speed sensor tone ring Excessive wheel bearing play or wear Debris or metallic contamination on tone ring Physical damage to wheel speed sensor mounting or air gap Missing or damaged tone ring teeth
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Derate Behavior
Power Derate
No
System Interactions
SPN 1241 FMI 7 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.
Related Faults in This Category
OEM System Resources
ASE Training Resources
Diagnostic Engine v7.0
Related Diagnostic Articles
Deep-dive diagnostic page: SPN 1241 FMI 7 — 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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