Powertrain, generic · Hybrid propulsion

P0B9A Hybrid/EV Battery Voltage Sense T Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B9A is the open-circuit code for sense T, the twentieth cell channel. GM uses it only on lithium-ion packs. The 2011 Volt compares adjacent cells for a difference above 1 V and checks the busbar cap voltage against 0.7 V; the 2016 Volt and ELR raise the adjacent-cell limit to 1.3 V, add a balancing-gate test below 36 mV and decide within 0.6 s, and the 2019 controller keeps those values but stretches the window to 0.8 s of 1.6 s, Type A in both cases. The 2012 two-mode trucks also have a channel T, their last nickel-metal hydride block 20, yet their tables carry range, low and high codes for it and no circuit code. A genuinely open lead usually means opening the high-voltage pack.

Likely causes

Open sense lead T at the cell tab or connector
Poor busbar or splice joint in the channel T path
Monitoring board input for channel T failed

Symptoms

  • MIL, hybrid or EV system warning
  • Ready mode or charging blocked

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 twiring harnessbms

Related codes

P0B9BP0B9CP0B9DP0B9EP0B95P0B9F

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