What it means
The cell balancing circuit F 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 (BMS) uses balancing circuit F to trim the charge difference between its assigned cell group and other groups. It monitors whether the F switching path responds when balancing is commanded; this code sets when that path remains inactive, such as from an open switch or circuit.
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
- Record freeze-frame data and BMS cell-group voltages, temperatures, and balancing status to see whether circuit F was being commanded and under what conditions.
- Compare the F group’s voltage with other groups and check whether charging or temperature conditions would prevent balancing.
- With the high-voltage system made safe according to the vehicle’s service procedure, inspect circuit F wiring and connectors for damage, looseness, or corrosion.
- Test the F balancing path for an open circuit using the manufacturer’s procedure and specification.
- If the wiring and switching path pass, have the BMS driver output for circuit F evaluated.
Common fixes
- Repair a loose or damaged circuit F connector.
- Repair open or damaged wiring in the circuit F harness.
- Replace a failed circuit F balancing switch or component.
- Repair or replace the BMS if its F-channel driver is faulty.
Can I keep driving?
Avoid relying on the vehicle’s full electric range or power, and do not continue a trip if it enters limp mode, will not charge, or shows a battery warning. Persistent imbalance can limit charging and power, so arrange prompt diagnosis by someone qualified to work on high-voltage systems.
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.