MG ZS (Gen2) U0140 Lost Communication With BCM

The U0140 Lost Communication With BCM indicates that one or more vehicle control modules have lost communication with the Body Control Module (BCM) over the Controller Area Network (CAN Bus). The BCM serves as the central controller for numerous body electrical systems, including central locking, lighting, power windows, keyless entry, immobiliser functions, wipers, interior lighting, and communication with the Engine Control Module (ECM), Transmission Control Module (TCM), ABS module, and instrument cluster. If communication with the BCM is interrupted for longer than the manufacturer’s specified time, the affected control module stores DTC U0140. This fault applies to the MG ZS Gen2 (ZS11 platform), introduced from 2024 onwards.

Symptoms

  • Check Engine Light may illuminate
  • Multiple warning lights displayed
  • Central locking inoperative or intermittent
  • Power windows or mirrors malfunction
  • Interior or exterior lighting faults
  • Keyless entry or remote locking inoperative
  • Immobiliser or starting issues
  • Wipers or other body electrical systems malfunction
  • Multiple communication-related DTCs stored
  • Loss of communication with the BCM during diagnostics

Possible Causes

  • Faulty Body Control Module (BCM)
  • CAN Bus wiring open circuit
  • CAN Bus short to ground or battery voltage
  • Damaged or corroded CAN Bus connectors
  • Poor BCM power supply
  • Faulty BCM ground connection
  • Blown fuse or faulty BCM relay
  • Low battery voltage
  • Water intrusion into the BCM or electrical connectors
  • Fault in another control module disrupting CAN Bus communication

Diagnosis

Diagnosis begins by confirming U0140 and performing a complete vehicle network scan using a compatible diagnostic scan tool to identify all stored communication-related fault codes. The technician should determine whether communication with the BCM can be established and identify any additional modules reporting network faults. Battery voltage, charging system output, BCM power supplies, fuses, relays, and ground circuits should be verified before inspecting the CAN High and CAN Low circuits for opens, shorts, excessive resistance, or abnormal voltage. Wiring harnesses and connectors should be inspected for corrosion, damaged terminals, loose connections, and water ingress. Manufacturer diagnostic procedures may also include CAN Bus network integrity testing, communication resistance measurements, module isolation, BCM software verification, and programming or configuration where required.

For vehicles operating in New Zealand, following OEM diagnostic procedures helps accurately distinguish between a faulty BCM, CAN Bus wiring problem, power supply issue, or another control module disrupting vehicle network communication before replacing expensive electronic components.

Accurately diagnosing this fault often requires manufacturer testing procedures, wiring diagrams, CAN Bus network schematics, connector pinouts, BCM power and ground specifications, communication network resistance values, BCM programming procedures, immobiliser configuration information, and system calibration data. Access to the factory service manual significantly reduces diagnostic time and helps prevent unnecessary parts replacement.

Applicable Years

2024, 2025, 2026, onwards

To order the correct OEM Service and Repair Manual for your MG ZS, submit your request using the form below, and our team will provide the ordering details.