Damaged, corroded or loose wiring and connectors in the CAN bus circuit between the battery energy control module and the rest of the network; Failed or intermittent power or ground supply to the battery energy control module, including blown fuses or bad grounds; Internal failure of the battery energy control module itself, often after moisture intrusion or heat damage; A shorted or open CAN data line caused by chafed harness insulation or a pinched wire near the battery pack; Another module on the same CAN segment holding the bus down and preventing communication with the battery module; Low or unstable 12-volt system voltage that disrupts module communication during cranking or heavy electrical loads

DTC codes / U01xx · Lost communication with a control module / U0112

U0112Lost Communication With Battery Energy Control Module 'B'

Q: What does code U0112 mean?

Lost Communication With Battery Energy Control Module 'B'. U0112 means the vehicle's main computer has lost the controller area network (CAN) communication link with the battery energy control module 'B', which is a high-voltage battery management controller used on hybrid and electric vehicles. The computer detects this when expected periodic messages from that module stop arriving, so it flags the module as offline rather than reporting a fault inside the battery itself.

U0112 means the vehicle's main computer has lost the controller area network (CAN) communication link with the battery energy control module 'B', which is a high-voltage battery management controller used on hybrid and electric vehicles. The computer detects this when expected periodic messages from that module stop arriving, so it flags the module as offline rather than reporting a fault inside the battery itself.

SystemNetwork

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaLost communication with a control module

Symptoms you may notice

Illuminated check engine light or service vehicle soon message, often with no other symptoms besides the warning light
Hybrid or electric system warning displayed, with the vehicle refusing to enter ready mode or start
Reduced power or limp-home mode because the high-voltage battery pack cannot be monitored
No charge or charging interrupted, since the battery energy control module cannot report pack status
Other unrelated warning lights or communication codes appearing because several modules share the same network
Intermittent warning that clears and returns, especially after rain, vibration or temperature swings

Common causes, most likely first

Damaged, corroded or loose wiring and connectors in the CAN bus circuit between the battery energy control module and the rest of the network
Failed or intermittent power or ground supply to the battery energy control module, including blown fuses or bad grounds
Internal failure of the battery energy control module itself, often after moisture intrusion or heat damage
A shorted or open CAN data line caused by chafed harness insulation or a pinched wire near the battery pack
Another module on the same CAN segment holding the bus down and preventing communication with the battery module
Low or unstable 12-volt system voltage that disrupts module communication during cranking or heavy electrical loads

How to diagnose and fix it

Scan all modules and record every stored code, then verify whether U0112 is current or history and whether other modules also report lost communication
Check the 12-volt battery condition and charging system voltage, since low voltage is a common cause of phantom communication codes
Inspect the battery energy control module connectors and harness for corrosion, loose pins, chafing or moisture intrusion, and clean and reseat them
Test the CAN bus resistance and voltage at the diagnostic connector and at the module to confirm the data lines are intact and not shorted
Check power and ground at the battery energy control module connector with a multimeter or test light under load
If wiring and power are good, substitute a known-good module or perform a module communication test to confirm internal failure before replacement
After repair, clear codes and verify communication returns, then road test and confirm no codes reset

Why the battery module drops offline

A weak or failing 12-volt battery frequently sets U0112 on hybrid and electric vehicles because the battery energy control module needs stable low-voltage power to stay awake on the network
Water intrusion into the battery pack area or a clogged drain can corrode the module connector and cause intermittent communication loss that only appears in wet weather
Technicians often replace the battery energy control module when the real fault is a chafed CAN wire rubbed through by a battery pack mounting bracket or a loose ground stud
U0112 can be a side effect of another module shorting the CAN bus, so always check whether multiple modules are offline before condemning the battery controller
Some vehicles set this code after a low-voltage event such as jump-starting or battery replacement, and it clears once the module reinitializes and communication is restored

Can I keep driving with U0112?

Do not continue driving if the vehicle will not enter ready mode or shows a high-voltage system warning, because the battery pack is not being monitored. If the car still drives but the warning is present, limit driving to a short trip to a repair shop and avoid heavy acceleration or charging until the fault is diagnosed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.