U0140 means Lost Communication With Body Control Module. A module on the vehicle network has stopped hearing from the body control module, which runs lighting, locks, wipers and other body functions. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What U0140 means
Modern vehicles have many control modules that share information over a network, usually called the CAN bus. Codes starting with U mean a module has stopped hearing another one, and voltage and processor codes mean a module is not getting clean power or has an internal fault. Low battery voltage, poor grounds, blown fuses and damaged wiring cause many of these codes, so test the battery and charging system first.
U0140 symptoms
- Lights, locks, wipers or the horn not working
- Security light or no-start on some vehicles
- Several warning messages
Common causes of U0140
- Body control module without power or ground
- Damaged network wiring
- Water intrusion in the module or connectors
- Low battery voltage
How to diagnose U0140
- Check battery voltage and the body control module fuses
- Inspect connectors for water and corrosion
- Check communication with the module on a scan tool
Can you drive with U0140?
It depends on what has stopped working; lights and a possible no-start can make it unsafe.
U0140 tips
Body control module communication faults often follow water leaks into the cabin, because the module and its connectors usually sit under the dash or in a kick panel. Look for wet carpet or corrosion.
Will U0140 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing U0140 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| U0100 | Lost Communication With ECM/PCM A |
| U0073 | Control Module Communication Bus A Off |
| U0155 | Lost Communication With Instrument Panel Cluster (IPC) Control Module |
Guides that help
When it is more than a sensor
Voltage and network codes come from wiring, the battery, the charging system or a module, not from engine or transmission wear. If a lost-communication code has left the transmission in limp mode, rule out the module and wiring before deciding the unit has failed, and see our transmissions only if testing confirms internal damage.
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