What it means
The cell balancing circuit K reports a stuck off 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
The battery management system uses balancing circuit K to trim small voltage differences in the cell group assigned to that channel. It monitors whether the K balancing path responds when balancing is commanded. This code sets when the module detects that the K path remains inactive, so that group may not be equalized.
Common causes
Most likely first.
- Open balancing switch or circuit
- Open or damaged 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
- Read freeze-frame data and battery-management live data, including the K balancing command and the assigned cell-group voltages, to see when the channel failed to respond.
- Compare the K cell-group voltage with neighbouring groups under the same operating conditions to check for an imbalance that persists while balancing is requested.
- With the high-voltage system made safe according to the vehicle’s service procedure, inspect the K balancing connector and harness for loose connections, corrosion, damage, or an open circuit.
- Test the K balancing switch and its wiring for continuity and unwanted resistance using the manufacturer's procedure and specification.
- If the K wiring and switch test correctly, have the battery management system driver and its command to channel K tested.
Common fixes
- Repair an open, damaged, or poorly connected K-channel wire or connector.
- Replace a failed K balancing switch or circuit component.
- Repair or replace the battery management system driver if testing confirms its failure.
Can I keep driving?
Because this fault can lead to reduced power, charging limits, or limp mode, avoid long trips and situations where sudden loss of propulsion would be hazardous. If power is restricted or charging fails, stop somewhere safe and arrange prompt hybrid or EV service; continued operation can allow cell-group imbalance to worsen.
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.