Powertrain, generic · Hybrid propulsion

P0B25 Hybrid/EV Battery A Voltage Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B25 sets when the voltage of hybrid/EV battery A drops below the window the controller expects. Bentley uses it in two different systems. In the 48 V Bentley Dynamic Ride anti-roll system it is stored in address 0021 (battery energy control module 2); if the highest and lowest cell readings differ by 0.5 V or more, an internal fault of the super capacitor is assumed and it is replaced. On the Bentayga and Flying Spur Hybrid the code appears in 008C, the high-voltage battery manager, with MIL and red battery warning, and the workshop must involve Bentley product support. GM checks pack undervoltage analogously with P0ABC (below 24 V). Unstable and high readings are P0B24 and P0B26. The driver loses roll control or battery power.

Likely causes

Internal fault of the energy store, e.g. Bentley 48 V super capacitor
Aged or unbalanced cells pulling the unit voltage down
Deep discharge after long standstill
Voltage measurement fault in the controller or sense leads

Symptoms

  • Bentley Dynamic Ride fault warning, roll control inactive
  • MIL on
  • Hybrid/EV system or high-voltage battery warning on
  • Battery power limited, less electric drive or assist

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–5,000
Time1–10 h

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

Parts involved

hv battery abms

Related codes

P0B23P0B24P0B26P0B29P0ABC

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.