P0DB2: Hybrid/EV Battery Cell Balancing Circuit B Stuck Off

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.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

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

Most 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

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Use the scanner to command the movement and compare the actual position with the requested one.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It affects emissions.

What each character of P0DB2 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
D: Subsystem depends on the code range
B2: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0DB2?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0DB2?

The most common causes are: bleed resistor of group B burnt open; balancing transistor of circuit B no longer switching; open terminal or cell tap connection in group B.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.