P0BBB: Hybrid/EV Battery Voltage Sense Z Circuit High

If the Z channel shows a cell voltage above the upper limit, the controller sets P0BBB. The 2016 Volt battery module uses 4.8 V or more for 1.4 s in a 2 s window, Type A, and checks first that the cell monitoring slave is communicating and no open sense line is reported. The 16OBDG02 programme fails above 4.90 V in 14 of 18 samples, and the eAssist mild hybrid fails above 4.65 V in seven of ten samples with a healthy 12 V supply, Type B over two trips. Lithium-ion cells are not meant to exceed these values, so the reading normally points to a short towards the higher neighbour, a faulty input or a corrupted measurement, and only rarely to a truly overcharged cell. Charging is stopped as a precaution.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

MIL and charging stopped
Reduced regeneration

Most likely causes

Sense lead Z shorted towards the higher neighbour cell
Faulty measuring input Z
Cell Z overcharged

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0BBB means

P: Powertrain: engine and transmission
0: Generic code: same on every make
B: Subsystem depends on the code range
BB: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0BBB?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0BBB?

The most common causes are: sense lead Z shorted towards the higher neighbour cell; faulty measuring input Z; cell Z overcharged.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.