U0139 Code – Lost Communication With Suspension Control Module B

on

Fault Code Description

The U0139 Diagnostic Trouble Code (DTC) indicates that one or more control modules have lost communication with Suspension Control Module B over the Controller Area Network (CAN) bus. This module is responsible for controlling specific functions of the electronic suspension system, such as damping adjustment, ride height, or adaptive suspension settings. When communication is interrupted, suspension performance may be reduced and the U0139 code will be stored.

Symptoms

  • Check Engine Light or suspension warning light illuminated.
  • "Service Suspension System" message displayed.
  • Adaptive suspension becomes unavailable.
  • Harsh or unstable ride quality.
  • Vehicle may remain at a fixed ride height.
  • Additional CAN communication DTCs may be stored.

Common Causes

  • Open or short circuit in CAN High or CAN Low wiring.
  • Blown fuse supplying Suspension Control Module B.
  • Poor battery voltage, power supply, or ground connection.
  • Loose, damaged, or corroded electrical connectors.
  • Faulty Suspension Control Module B.
  • Incorrect module programming after replacement.

Severity

Severity: Moderate. The vehicle is generally safe to drive, but adaptive suspension functions may be disabled, resulting in reduced ride comfort, handling performance, and vehicle stability.

Average Repair Cost

  • CAN bus wiring repair: $100–$350
  • Power or ground circuit repair: $80–$250
  • Connector cleaning or replacement: $50–$200
  • Fuse replacement: $10–$50
  • Suspension Control Module programming: $100–$300
  • Suspension Control Module replacement: $400–$1,500+

Diagnosis

  1. Scan all vehicle modules for stored DTCs.
  2. Inspect the suspension module fuse.
  3. Verify battery voltage, power, and ground circuits.
  4. Inspect CAN High and CAN Low wiring.
  5. Check connectors for corrosion or loose terminals.
  6. Verify communication using a professional scan tool.
  7. Reprogram or replace Suspension Control Module B if necessary.

Common Repairs

  • Repair damaged CAN bus wiring.
  • Replace blown fuses.
  • Repair power or ground circuits.
  • Clean or replace damaged electrical connectors.
  • Reprogram Suspension Control Module B.
  • Replace Suspension Control Module B if confirmed faulty.

Comments

Post a Comment