What it means
The cell balancing circuit G 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
Balancing circuit G controls a switching path the BMS uses to reduce charge differences in its assigned cell group. The BMS checks that the path turns off when required; this code sets when the G channel remains active, which can result from a stuck switch, shorted wiring, or a failed driver.
Common causes
Most likely first.
- Balancing switch or driver stuck on
- Shorted balancing-circuit wiring
- BMS driver 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
- Capture freeze-frame data and live G-channel status to confirm when the BMS expected balancing to stop and what the cell-group voltage and temperature were.
- Compare the G group with other groups and check whether the BMS is still commanding balancing under the recorded conditions.
- With the high-voltage system made safe according to the service procedure, inspect G-channel wiring and connectors for shorts, damage, or contamination.
- Test whether the G switching path remains conductive when it should be off, following the manufacturer’s procedure and specification.
- If the switch and wiring are sound, test the BMS driver controlling circuit G.
Common fixes
- Repair a short or damaged connector in the G-channel wiring.
- Repair shorted G-channel harness wiring.
- Replace a G balancing switch that is confirmed stuck on.
- Repair or replace the BMS if its G-channel driver is stuck on.
Can I keep driving?
Limit driving and avoid charging until the fault is assessed, since a G-channel path that stays on can worsen cell-group imbalance. Stop if power is reduced or a battery warning appears, and have the high-voltage system inspected promptly.
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.