Powertrain, generic · Hybrid propulsion

P0B31 Hybrid/EV Battery D Voltage Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B31 is stored when the voltage of hybrid/EV battery D stays below the expected range. High voltage of the same unit sets P0B32, fluctuation P0B30 and an unspecified deviation P0B2F. No manufacturer publishes a definition of P0B31; Bentley's P0B25 for battery A is the closest documented example, with the energy store replaced once the cell spread reaches 0.5 V. GM uses P0ABC for an undervoltage of the whole pack (below 24 V). CARB asks for monitoring of cells and voltage sensors in hybrid storage and for fault codes that single out the replaceable unit. Typical is a module in unit D that has aged faster or self-discharged during standstill. Discharge power and electric range drop, and the controller may stop electric driving.

Likely causes

Aged cells with lost capacity in battery D
Deep discharge or self-discharge after standstill
Voltage measurement fault in the controller or sense leads

Symptoms

  • Hybrid/EV system or high-voltage battery warning on
  • MIL on
  • Battery power limited, less electric drive or assist
  • Reduced electric range

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–4,000
Time1–10 h

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

Parts involved

hv battery dbms

Related codes

P0B2FP0B30P0B32P0B25P0B2DP0ABC

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.