P0BA4: Hybrid/EV Battery Voltage Sense V Circuit

P0BA4 reports an open or poorly connected sense V lead, the twenty-second channel and the last before W begins at P0BA9. GM's 2019 battery energy control module recognises it through seven cases, including 1.3 V between neighbouring cells, less than 36 mV with the balancing gate on and splice voltages above 0.1 or 0.5 V, with 0.8 s of failure in 1.6 s, Type A. The 2011 Volt already listed P0BA4 among its open sense line codes. In GM's 16OBDG02 programme a measured line resistance above 30.00 in 7 of 9 samples triggers it, in the eAssist mild hybrid low readings on lines N and N-1 together with a 0.5 V jump, Type B, gated by P1B38. Without a good sense lead the pack cannot balance or protect that cell.

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 hybrid or EV system warning
Vehicle may not become ready to drive
Charging blocked

Most likely causes

Broken or unplugged sense lead V
High-resistance splice or busbar joint on channel V
Cell monitoring board fault on channel V

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
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 P0BA4 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
B: Subsystem depends on the code range
A4: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0BA4?

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 P0BA4?

The most common causes are: broken or unplugged sense lead V; high-resistance splice or busbar joint on channel V; cell monitoring board fault on channel V.

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.