Code Definition

U0140 — Lost communication with Body Control Module (BCM)

System: Network Communication  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About U0140

U0140 is a generic (obd-ii standard) network communication diagnostic trouble code. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

Scanning & clearing: Network (U) codes report communication faults between modules. When diagnosing U-codes, checking the vehicle's CAN bus integrity, supply/ground at each module, and reading all modules for related faults is usually the first step.

Because U0140 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Body Control Module (BCM) manages the vehicle body electrical functions including exterior and interior lighting, central locking, power windows, wipers, horn, and alarm, and on most platforms it also forms part of the immobiliser and controls the vehicle sleep and wake strategy. It broadcasts the status of those functions onto the CAN data bus, and DTC U0140 is stored by another module when the expected periodic messages from the BCM stop arriving, either at ignition on or during vehicle operation. The BCM is usually mounted low in the cabin behind a kick panel, under the dash, or beside ...

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