U0111: Lost Communication With Battery Energy Control Module A
What does U0111 mean?
U0111 is a network communication fault that indicates the vehicle's main control system can no longer talk to Battery Energy Control Module A over the communication bus. This module typically manages battery monitoring, energy distribution, or hybrid and EV battery systems depending on your vehicle. When communication drops out, the ECU logs this code because it is receiving no data where it expects a regular signal.
The most common causes are a wiring fault between the module and the CAN bus, a blown fuse in the relevant circuit, a corroded or loose connector at the module itself, or the module has failed outright. Before assuming the module is dead, check the basics: inspect the connector for corrosion or spread pins, verify the fuse is intact, and look for any damaged wiring in the harness leading to the module.
Because this code is rated low severity, the vehicle will generally remain driveable, but you should not ignore it long term. If your car has a hybrid or electric battery system, a communication gap here can affect energy management and reduce efficiency. Scan for any additional codes that may point to a root cause, clear the fault, and see if it returns. If it does, a thorough wiring inspection or module replacement is the next step.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- Possible issues with communication bus operation
- Vehicle may enter reduced power mode (limp mode)
Estimated repair cost
Typical range in Australia (parts + labour)
Common causes
- Failed control module
- CAN bus wiring fault or short
- Blown fuse to the affected module
- Water intrusion in a connector or module
- Battery voltage too low
What should you do?
This is a minor or informational code. Monitor for any changes in vehicle behaviour and address it during your next scheduled service visit.
Get a diagnosis for YOUR car
Code U0111 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.