What it means
The BMS detects a circuit low fault on voltage sense channel G 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 BMS reads a cell group in the high-voltage battery using voltage sense channel G. This code sets when channel G's signal falls below the expected circuit level, leaving the BMS unable to trust that cell-group voltage reading.
Common causes
Most likely first.
- Short to ground in voltage-sense wiring
- Open or high resistance in voltage-sense wiring
- Loose, damaged, or corroded connector
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 and BMS data, then compare channel G's reading with adjacent cell-group readings to confirm whether it is unusually low.
- Use the manufacturer's high-voltage isolation procedure before inspecting any battery sense wiring or connectors.
- With the battery isolated as specified, inspect channel G wiring and connectors for a short to ground, loose terminals, corrosion, or visible damage.
- Test channel G for a short to ground, an open, or excessive resistance according to the manufacturer's procedure and specification.
- If the harness and connector pass, use the manufacturer's diagnostic checks to assess channel G's sensing input and BMS circuitry.
Common fixes
- Reseat a loose channel G connector using the specified isolation procedure.
- Repair corroded or damaged channel G connector terminals.
- Repair or replace channel G wiring that is shorted to ground, open, or high resistance.
- Repair or replace the sensing or BMS circuitry if testing confirms an internal fault.
Can I keep driving?
If power is reduced, limp mode is active, or charging is refused, avoid relying on the vehicle for a long trip; the BMS cannot trust channel G's cell-group reading. Arrange prompt diagnosis and stop driving if power loss makes operation unsafe.
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.