U0140: Lost Communication With Body Control Module
Other modules have stopped hearing from the body control module, which runs things like lights, locks and some security functions.
What U0140 means
The body control module runs many comfort and convenience features: lights, power locks, windows, wipers, the horn and often part of the security system. It also passes messages between other modules on some vehicles. U0140 means other modules, often the engine computer or instrument cluster, have stopped receiving messages from the BCM. Symptoms vary a lot by vehicle, from lights or locks that stop working to a security light and a no start. KBB recommends having it scanned and repaired quickly, and notes driving is not advisable if the code is affecting driveability. A weak battery, blown fuse, bad ground and corroded connectors are common causes. Because the BCM is often mounted low under the dash or in a kick panel, water from clogged drains or leaks can damage it. Shops check battery voltage, fuses, power and grounds at the BCM, then test the network wiring. If the module still will not respond, it is replaced and programmed to the vehicle.
Common symptoms
- Several warning lights on
- Interior or exterior lights not working or staying on
- Power locks, windows or wipers acting up
- Security light on or no start on some vehicles
- Battery draining overnight
Most common causes
- Weak battery or low voltage
- Blown fuse or failed power feed to the BCM
- Bad ground at the BCM
- Corroded connector, often from a water leak
- Damaged network wiring
- Failed body control module
What to check yourself first
Have the battery tested. Check the fuses that feed the body control module, often in the interior fuse box. Look for water leaks near the BCM location, such as under the dash or kick panel, from a clogged cowl drain or sunroof drain.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace battery | $456-$493 | A weak battery or low voltage is a very common cause of communication codes. |
| Network (CAN bus) electrical diagnosis | $122-$179 | Network faults are usually found by checking power, ground and the two CAN bus wires at each module. |
| Replace body control module | $702-$762 | Only after power, ground and wiring are confirmed good. The new module usually needs programming. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- U0100 Lost Communication With ECM/PCM "A"
- U0155 Lost Communication With Instrument Panel Cluster (IPC) Control Module
- U0121 Lost Communication With Anti-Lock Brake System (ABS) Control Module
- U0073 Control Module Communication Bus "A" Off
- P0562 System Voltage Low