Powertrain, generic · Hybrid propulsion

P0BA9 Hybrid/EV Battery Voltage Sense W Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0BA9 opens the W group, the twenty-third cell voltage channel, and flags a sense lead that is open or badly connected. GM's 2019 battery energy control module checks seven cases, ranging from a reading under 36 mV while the balancing gate of that cell is switched on to at least 1.3 V between neighbouring cells and splice voltages above 0.1 V or 0.5 V at busbar joints; 0.8 s of failure within 1.6 s sets it as Type A. The 2016 Volt module uses a 0.6 s window instead. GM's eAssist mild hybrid needs readings under 1.4 V on lines N and N-1 plus a change of more than 0.5 V within 200 ms in seven of ten samples, Type B. With the lead lost, the cell behind it can neither be balanced nor protected.

Likely causes

Broken, chafed or unplugged sense lead W
High-resistance busbar or splice joint at channel W
Failed input on the cell monitoring board for W

Symptoms

  • MIL with hybrid or EV system warning
  • Reduced propulsion power or no ready mode
  • Charging interrupted or refused

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–7,000
Time1–10 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery voltage sense wwiring harnessbms

Related codes

P0BAAP0BABP0BACP0BADP0BA4P0BAE

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.