What it means
The BMS detects a circuit high fault on voltage sense channel N 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 battery management system reads a cell group's voltage through sense channel N and checks that the signal stays within its expected electrical range. P0B7F sets when channel N is detected above that range, making that group's voltage reading unreliable.
Common causes
Most likely first.
- Sense wire shorted to higher voltage
- Reference regulator 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
- Save freeze-frame data and compare channel N's live reading with adjacent cell-group voltages to see whether the high signal is persistent or appeared under a particular condition.
- Check for charging limits or reduced propulsion, which can be imposed when the BMS cannot verify channel N's group voltage.
- With the high-voltage battery safely isolated under the vehicle's service procedure, inspect channel N wiring and connectors for damage, contamination, or corrosion.
- Have a qualified hybrid technician test channel N for a short to a higher-voltage circuit and check its reference supply using the manufacturer's procedure.
- If wiring and reference checks are satisfactory, compare the channel N input at the battery monitoring module with the actual group voltage to assess a module fault.
Common fixes
- Repair channel N wiring that is shorted to a higher-voltage circuit.
- Repair a faulty reference regulator if its output is confirmed outside the manufacturer's specification.
- Clean or replace corroded or damaged channel N connector terminals.
- Replace or repair the battery monitoring module if its channel N input remains high with sound wiring and reference supply.
Can I keep driving?
Drive only as needed to reach a safe location or service, and avoid long trips or relying on electric-only operation because power and charging may be restricted. Stop if power drops sharply or the vehicle displays additional high-voltage warnings.
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.