What it means
The high-voltage system voltage is above the expected window. Regenerative braking overshoot or BMS regulation fault.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The high-voltage battery supplies the vehicle's electric drive and hybrid functions, while the battery management system monitors pack voltage during operation and energy recovery. This code sets when measured system voltage rises above its expected range, potentially causing the vehicle to limit power or regenerative braking.
Common causes
Most likely first.
- HV battery cells aged
- BMS regulation outside calibration
Symptoms
- Check-engine or hybrid-system warning light may be on
- Reduced power or limited vehicle operation
- Regenerative braking may be limited
How to diagnose it
- Read freeze-frame data and hybrid-system fault codes to determine whether the high reading occurred during regenerative braking or under another operating condition.
- Use a compatible scan tool to review pack voltage and battery-section readings, comparing them with the manufacturer's expected values for the recorded conditions.
- Check for related battery-management, charging, and regenerative-braking faults that could explain an over-range voltage event.
- Have the high-voltage battery and its connections inspected using the manufacturer's safety procedures; do not probe high-voltage components yourself.
- If the battery readings do not identify the cause, check battery-management system sensing and regulation against the manufacturer's specification.
Common fixes
- Repair a verified battery sensing or connection fault using the required high-voltage safety procedures.
- Correct a confirmed regenerative-braking control issue if it is driving the voltage rise.
- Replace a battery module or pack only if testing confirms a cell or pack fault.
- Repair or update battery-management system control as directed by manufacturer diagnostics.
Can I keep driving?
Drive cautiously and leave extra stopping distance if regenerative braking is reduced; avoid relying on it to slow the vehicle. If power becomes limited or a high-voltage warning appears, stop safely and arrange assessment by a qualified hybrid technician.
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.