Powertrain, generic · Hybrid propulsion

P0B44 Hybrid/EV Battery Voltage Sense B Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B44 is the J2012 slot for a cell voltage channel B whose reading jumps or drops out for short moments rather than failing permanently. No manufacturer documents P0B44 publicly. For orientation, GM's 2019 tables check channel B for open sense lines (P0B40), frozen values compared with the other cells (P0B41) and fixed limits of 0.2 V and 4.8 V (P0B42, P0B43); an erratic monitor would add a test for implausible steps between samples. CARB requires the storage system's voltage sensors to be monitored as inputs and faults to be pinpointed to the smallest replaceable unit. Typical causes are vibration-loosened cell taps and connectors on the monitoring board. Warnings may come and go with driving conditions.

Likely causes

Loose or cracked cell tap connection
Fretting or vibration damage at the monitoring board connector
Electrical noise from inverter or motor coupling into the sense lines

Symptoms

  • MIL or hybrid warning that comes and goes
  • Occasional loss of electric drive or assist

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–6,000
Time0.5–8 h

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

Parts involved

hv battery voltage sense bwiring harnessbms

Related codes

P0B40P0B41P0B42P0B43P0B3FP0B18

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