U0140 on Cadillac: How to Diagnose & Fix
Lost Communication with BCM
1 Cadillac model · 1 documented issue
U0140 on Cadillac by model: symptoms, diagnosis and fix
As a hand-built, technology-flagship vehicle, the Celestiq experiences occasional software integration issues between its numerous systems including the 55-inch LED display, four-zone smart glass roof, and advanced driver assistance features. Individual systems may temporarily lose communication with each other, requiring a vehicle restart.
Common Symptoms
- Display panels showing incorrect information
- Smart glass roof not responding
- Driver assist features temporarily unavailable
- System communication warnings
How to Fix
Given the Celestiq's bespoke nature, all service should be performed at authorized Cadillac dealers with Celestiq certification. OTA updates address the majority of software integration issues. The concierge service team can remotely diagnose many issues. Keep the vehicle connected to Wi-Fi for timely update delivery.
Sources for this issue (1)
U0140 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U0140 mean on a Cadillac?
U0140 stands for "Lost Communication with BCM." U0140 is a network communication code meaning a module has lost communication with the body control module (BCM) over the vehicle's data bus. The BCM oversees many body and convenience functions — lighting, door locks, windows, wipers, anti-theft, and gateway communications — so losing contact with it can cause a wide range of seemingly unrelated electrical problems and warning lights. This is typically a wiring, connector, power/ground, or bus fault, or a failure of the BCM itself. Because the BCM often acts as a communication hub, this code can appear alongside other 'lost communication' codes. On Cadillac it is documented across 1 model: Celestiq.
What are the most common causes of U0140?
The most common causes of U0140 are: Loss of power or ground to the BCM, CAN/data bus wiring damage, short, or open circuit, Corroded, loose, or damaged BCM connectors, Blown fuse feeding the BCM, Failed body control module, Water intrusion or corrosion in the harness, Another module faulting the shared data bus. The specific cause varies by vehicle.
How much does it cost to fix U0140 on a Cadillac?
Repair costs vary widely with the root cause and Cadillac model; each issue on this page carries its own estimate where one is published.
Looking for U0140 on a different make?
View U0140 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.