AI Diesel Tech

Fault Code Reference

SPN 1437 FMI 2ABS

Traction Control System - Data Erratic, Intermittent or Incorrect

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Overview

Fault Code

SPN 1437 / FMI 2

Category

ABS

Derate Risk

No

Regen Inhibit

No

Inducement Risk

No

Component Location: Wheel speed sensors are mounted at each wheel hub assembly with wiring routed to the ABS control module typically mounted on the frame rail.

Common Symptoms

  • ABS warning light illuminated on dash
  • Traction control warning light active
  • Intermittent loss of traction control function
  • ABS system disabling unexpectedly during operation
  • Erratic wheel speed readings displayed

Root Causes

  • Faulty wheel speed sensor or tone ring damage Intermittent wiring harness connection or corrosion ABS control module communication issue Damaged or contaminated wheel speed sensor reluctor ring Water intrusion in wheel speed sensor connector

Full step-by-step tests, DVOM guidance, and pinout data are available inside the AI Diesel Tech diagnostic session.

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Derate Behavior

Power Derate

No

System Interactions

SPN 1437 FMI 2 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.

Deep-dive diagnostic page: SPN 1437 FMI 2 — Full FSM Sequence & Repair Steps — includes wiring notes, sensor specs, and gated repair procedures.

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