Powertrain, generic · Hybrid propulsion

P0B8A Hybrid/EV Battery Voltage Sense P Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B8A is the erratic-signal member of the channel P group. There is no public manufacturer documentation for it: GM describes open, rationality, low and high diagnostics for sense P in its 2016 and 2019 tables, but none for an intermittent signal, and the Ford bulletins stop at channel N. The code exists because CARB 1968.2 requires the voltage sensors of a hybrid battery to be monitored and malfunctions to be stored under distinct codes. If set, the picture would be a channel P value that briefly drops out or spikes, for instance through a fatigued wire near a bend in the sense harness or a connector that loses contact when the pack warms up. Readings in live data may look normal between the events.

Likely causes

Fatigued wire at a bend of the sense harness
Connector losing contact as the pack warms up
Sporadic fault in the cell monitoring chip

Symptoms

  • Warning lamp that goes out again
  • Occasional engine start without demand on hybrids

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–5,000
Time1–8 h

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

Parts involved

hv battery voltage sense pwiring harnessbms

Related codes

P0B86P0B87P0B88P0B89P0B85P0B8F

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.