What it means
The BMS detects a circuit 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 voltage through battery voltage sense channel G. This code indicates a fault in the channel G circuit, so the BMS cannot treat that cell-group voltage measurement as reliable.
Common causes
Most likely first.
- Open or short in voltage-sense wiring
- Loose, damaged, or corroded connector
- Fault in the battery voltage-sensing or control circuitry
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 groups and note any related battery codes.
- Check the manufacturer's high-voltage isolation procedure before touching battery sense connectors or wiring.
- With the battery isolated as specified, inspect channel G's connectors and accessible harness for looseness, corrosion, pin damage, opens, or shorts.
- Test channel G wiring for continuity, shorts, and excessive resistance using the manufacturer's diagnostic procedure and specification.
- If the circuit checks pass, follow the manufacturer's procedure to test the channel G sensing input and BMS circuitry.
Common fixes
- Reseat a loose channel G connector using the specified isolation procedure.
- Clean or repair corroded or damaged channel G connector terminals.
- Repair or replace channel G wiring with an open, short, or high-resistance connection.
- Repair or replace the battery sensing or BMS circuitry if diagnosis identifies an internal fault.
Can I keep driving?
Treat reduced power, limp mode, or charging problems as signs the BMS may be limiting battery use because channel G cannot be trusted. Avoid long trips or relying on electric range until the fault is diagnosed, and stop if the vehicle becomes unsafe to control.
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.