Powertrain, generic · Hybrid propulsion

P0B8B Hybrid/EV Battery Voltage Sense Q Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B8B marks an open circuit on voltage sense Q, the seventeenth channel. In GM's BAS Plus mild hybrid tables Q is the first channel whose open test is blocked by code P1B37 instead of P1B36, which suggests it sits in the next measuring group of the battery interface module; the criterion stays lines N and N-1 below 1.4 V with a change above 0.5 V in 200 ms, 7 of 10 samples, Type B. GM's 2019 battery controller uses 0.8 s in a 1.6 s window, the 2016 version 0.6 s, both Type A with the 1.3 V and 36 mV criteria. The 2011 Volt list includes P0B8B as well. The two-mode NiMH trucks have no circuit code for block 17. Ford does not list it. Typically the vehicle restricts or blocks electric operation until repaired.

Likely causes

Sense lead Q open between cell tap and module
Loose or corroded connector at the second measuring group
Fault in the battery interface module

Symptoms

  • MIL and service vehicle message
  • Electric operation blocked or limited
  • Fuel consumption rises on hybrids

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–6,500
Time1–10 h

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

Parts involved

hv battery voltage sense qwiring harnessbms

Related codes

P0B8CP0B8DP0B8EP0B8FP0B86P0B90

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