Powertrain, generic · Hybrid propulsion

P0B8D Hybrid/EV Battery Voltage Sense Q Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B8D reports a voltage on sense Q below the lowest credible cell value. GM's lithium-ion battery controllers in the 2016 and 2019 tables use 0.2 V or less for 1.4 s within 2 s, Type A, and the 2016 program with a separate sense module 0.20 V with 14 of 18 samples. GM's BAS Plus mild hybrid applies 1.4 V, 7 of 10 samples, Type B. In the 2012 two-mode NiMH pack Q is block 17 and the battery pack control module requires blocks 17 and 18 both under 2 V for 15 of 20 samples. The low test is suppressed while an open-line fault is active, so P0B8B takes precedence for a broken lead. Shorts in the sense path are the leading cause; a real deep discharge of the cell would normally trigger further battery codes too.

Likely causes

Short in the Q sense path to a lower potential
Sense module input reading low
Cell or block 17 deeply discharged

Symptoms

  • MIL and reduced power mode
  • Engine runs more often on hybrids

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–6,000
Time1–8 h

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

Parts involved

hv battery voltage sense qwiring harnessbms

Related codes

P0B8BP0B8CP0B8EP0B8FP0B88P0B92

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