DTC codes / P0Dxx · Hybrid propulsion / P0DD9
P0DD9 indicates that the battery management system has detected the cell balancing circuit for the 'L' phase or group stuck in the active state, meaning it cannot turn off the balancing current for that section of the high-voltage battery. The computer monitors the balancing circuit's control line and sees it remain energized even when commanded off, which can lead to uneven cell voltages and potential overheating of the balancing resistor.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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