What it means
The cell balancing circuit A reports a stuck on condition. Cell-group voltage equalization may be impaired on this channel.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery balancing circuit A should switch on only when the battery management system commands it to equalize the cell groups assigned to that channel. This code sets when the system detects that circuit A remains active when it should be off, which can point to a stuck balancing switch, an internal battery or control fault, or a wiring problem.
Common causes
Most likely first.
- Balancing switch stuck on
- Battery pack or BMS internal fault
- Wiring or connector fault
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and review battery-management status to confirm whether balancing circuit A is reported on when it is not commanded.
- Compare the voltage trend of cell groups assigned to circuit A with balancing commands to check for continued equalization.
- With the vehicle powered down according to the manufacturer’s procedure, inspect accessible circuit A connectors and wiring for damage, moisture, or unintended contact.
- Use the wiring diagram and specified procedure to check whether circuit A’s control or output remains active when it should be off.
- If the wiring is sound, have the balancing switch and battery management system assessed for an internal fault.
Common fixes
- Repair damaged or pinched wiring in the circuit A balancing path.
- Correct a loose or contaminated circuit A connector.
- Replace the balancing switch if it is confirmed stuck on.
- Repair the battery pack or battery management system if an internal fault is confirmed.
Can I keep driving?
Avoid extended driving if charging is restricted, power is reduced, or the warning persists, because continued unintended balancing can worsen cell-group imbalance. Arrange prompt diagnosis and do not open or probe the high-voltage battery pack.
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.