What it means
A control module has lost communication with battery energy control module B. On applicable vehicles, battery-related functions may be limited or unavailable.
How it works
Battery energy control module B is a separately designated battery-control module on vehicles that use more than one. Other modules expect messages from this specific module over the vehicle network; U0112 sets when those messages are missing. It does not mean that battery energy control module A has failed or prove that the battery itself is defective.
Common causes
Most likely first.
- Loss of module power or ground
- Open, shorted, or damaged communication wiring or connector
- Module or gateway fault
Symptoms
- Hybrid or electric system warning
- Reduced or unavailable vehicle functions may occur
- Communication faults in other modules
How to diagnose it
- Save the all-module scan and freeze-frame data, distinguishing reports of lost communication with module B from faults naming module A.
- Check the 12-volt battery and the fuses, power, and ground connections assigned specifically to battery energy control module B.
- Inspect module B's accessible low-voltage connector and network wiring for corrosion, loose pins, water entry, or harness damage.
- Use a compatible scan tool to check whether module B responds and whether related modules report the same communication loss.
- If its low-voltage supply is correct but it remains offline, test the network circuit and gateway route for module B to the manufacturer's specification.
Common fixes
- Restore a weak 12-volt battery or poor battery connection.
- Replace a failed fuse or repair the power or ground connection assigned to module B.
- Repair damaged network wiring or clean and secure module B's accessible connector.
- Correct a confirmed gateway fault that blocks communication with module B.
- Replace or reprogram battery energy control module B only after its power and network circuits check out.
Can I keep driving?
If a hybrid or electric system warning or reduced function appears, limit driving to what is needed to reach a safe location because vehicle operation may become restricted. Stop if propulsion is unreliable, and do not handle high-voltage components.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.