Powertrain, generic · Hybrid propulsion

P0B9B Hybrid/EV Battery Voltage Sense T Circuit Range/Performance

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

On the 2012 two-mode trucks sense T is block 20, the last of their twenty nickel-metal hydride blocks, and P0B9B shows how GM handles the missing neighbour: block 20 alone is multiplied by twenty and compared with the pack voltage, and a gap above 70 V in 160 of 170 samples sets the code as Type B. All other channels there use a pair of blocks. On lithium-ion packs the code means that cell T does not follow the pack average: the 2019 hybrid processor demands 0.005 V of movement when the average shifts by more than 0.022 V (35 of 40 samples, Type A), the 2016 Volt the same with a 7 s in 8 s window, and eAssist half the average movement in 20 of 40 samples, Type B.

Likely causes

Channel T measurement stuck or sluggish

Block 20 voltage diverging from pack voltage on two-mode NiMH packs

Faulty pack voltage reference used for the comparison

Symptoms

MIL, drivability usually unchanged
Hybrid assist or EV range slightly reduced

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€80–5,000

Time0.5–6 h

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

Parts involved

hv battery voltage sense twiring harnessbms

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