What it means
The HV battery pack sensor module reports an internal fault. Cell-level voltage and temperature monitoring may be impaired.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid battery pack sensor module gathers cell-voltage and temperature readings for the battery management system (BMS). The BMS sets P0AFC when it reports an internal sensor-module fault that can compromise those readings; a lost BMS communication link or cell imbalance may also accompany the fault.
Common causes
Most likely first.
- Internal sensor module fault
- Communication lost with BMS
- Pack cell imbalance approaching service threshold
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 scan all hybrid and battery modules for communication or cell-balance codes to see whether P0AFC is isolated or part of a wider pack fault.
- Compare live cell-voltage and temperature readings for missing, implausible, or outlying values that could point to a monitoring problem or pack imbalance.
- With the vehicle made safe according to its service information, inspect accessible low-voltage connectors and harnesses serving the battery sensor module for looseness, corrosion, or damage.
- Check BMS communication and module power and ground circuits using the wiring diagram and the manufacturer's specifications.
- If wiring and communication are sound, use the manufacturer's diagnostic procedure to confirm whether the sensor module itself has failed or the pack has a cell imbalance.
Common fixes
- Repair a loose, corroded, or damaged sensor-module connector or low-voltage harness.
- Repair a verified power, ground, or BMS communication circuit fault.
- Replace the battery pack sensor module if its internal fault is confirmed.
- Service or replace the battery pack if testing confirms cell imbalance beyond the manufacturer's service limits.
Can I keep driving?
Avoid relying on electric-only operation or attempting long trips: reduced power or a charging restriction may occur without warning. Have the hybrid system checked promptly, and do not open or probe the high-voltage battery pack.
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.