Powertrain, generic · Hybrid propulsion

P0DB2 Hybrid/EV Battery Cell Balancing Circuit B Stuck Off

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Stuck off on circuit B (P0DB2) is the passive failure: the command arrives, but the bleed resistor of that group carries no current, so its high cells are never trimmed. LG Chem's patent EP2730933A1 tests for this by switching the balancing circuit on and off and watching how the voltage across a diagnosis resistor reacts; no change means a dead circuit. The result builds up over many charges: cells of group B reach the upper limit first and end charging early, while the rest stay below. CARB 13 CCR 1968.2 counts this as a balancing malfunction. Ford lists P0DB2 in its 2016 hybrid OBD summary: the BECM bleeds only the highest cells down to the others and judges each six-cell circuit once per power-up against a 75 mV limit. Compare P0DB1 for the opposite fault.

Likely causes

Bleed resistor of group B burnt open
Balancing transistor of circuit B no longer switching
Open terminal or cell tap connection in group B

Symptoms

  • MIL and battery warning
  • Charging stops before the expected state of charge
  • High cell voltages in group B in live data

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–4,000
Time2–8 h

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

Parts involved

hv battery cell balancing circuit bbms

Related codes

P0DABP0DB0P0DB1P0DB3P0DAE

References: law.cornell.edu, patents.google.com, fordservicecontent.com.