What it means
The BMS detects a circuit intermittent/erratic fault on voltage sense channel B of the high-voltage battery. Cell-group voltage measurement is unreliable 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 monitors voltage sense channel B for a stable reading from its cell group. This code sets when that reading fluctuates or becomes erratic, often as a loose connection or damaged wire briefly interrupts the signal.
Common causes
Most likely first.
- Loose or corroded connector
- Damaged wiring with an intermittent connection
- Fault in the battery voltage-sensing module
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 live channel B voltage while monitoring neighboring groups for sudden jumps or dropouts.
- With the vehicle powered down using the manufacturer’s high-voltage safety procedure, visually inspect channel B wiring and connectors for chafing, corrosion, poor seating, or movement-related damage.
- Check accessible channel B connector terminals for looseness or corrosion that could interrupt the signal intermittently.
- Have a qualified technician check channel B continuity and circuit stability using the manufacturer’s procedure, while following its approved harness movement checks.
- If the wiring and connector remain stable, have the battery voltage-sensing module checked for intermittent channel B faults.
Common fixes
- Reseat or clean a loose or corroded channel B connector.
- Repair chafed or damaged channel B wiring that causes an intermittent connection.
- Restore a poor terminal or splice connection in the channel B sense circuit.
- Replace or repair the battery voltage-sensing module if testing confirms an intermittent fault.
Can I keep driving?
If the warning is accompanied by reduced power, limp mode, or charging trouble, avoid unnecessary trips because the fault can recur and limit propulsion. Do not handle high-voltage battery wiring; arrange prompt diagnosis.
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.