What it means
The supply voltage circuit of the HV battery pack cooling fan reports a circuit high condition. Cooling fan operation 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 cooling fan uses a supply circuit to power airflow through the battery pack. P0BC1 sets when the monitored supply voltage is higher than expected, a condition that can disrupt fan operation or damage related components.
Common causes
Most likely first.
- Wire shorted to higher voltage
- Alternator overvoltage
- Connector pins corroded - high contact resistance
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
- Review freeze-frame data and live fan-command and supply readings to determine when the high reading occurs.
- With the vehicle powered down as specified by the manufacturer, inspect the fan supply harness and connector for damage or contact with a higher-voltage circuit.
- Check the charging-system and fan supply readings using the manufacturer’s procedures to see whether the supply source is overvoltage.
- Test the fan supply circuit for a short to a higher-voltage feed and compare readings with the manufacturer’s specification.
- If wiring and supply levels pass, follow the manufacturer’s diagnostic procedure to check the fan and control circuit.
Common fixes
- Secure the fan supply harness away from higher-voltage wiring.
- Repair corroded or damaged supply connector contacts.
- Repair a wire shorted to a higher-voltage circuit.
- Correct an overvoltage supply condition if confirmed by testing.
- Repair the fan or control circuit if the supply wiring and source test correctly.
Can I keep driving?
Avoid long trips and charging until the fault is assessed, since the fan may not operate correctly and the pack could overheat. Stop if a battery temperature warning or reduced-power alert appears.
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.