P0DB5Hybrid/EV Battery Cell Balancing Circuit C Stuck On
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Circuit C stuck on (P0DB5) means the cells of group C bleed energy permanently, also with the car switched off. Designers guard against exactly this: the LaunchPoint patent US8598840B2 lets every balance enable expire on a timer unless the central controller renews it, so a lost command cannot leave a switch on. When the hardware itself fails closed, that guard does not help and the controller can only spot the falling voltage or the mismatch between command and switch state. Over a few days the group C cells can drop far enough to trigger low cell voltage codes. Ford's 2017 hybrid OBD summary tests circuit C in a 100 ms window each time the car wakes, contactors still open, and sets P0DB5 if one of its six cells is more than 75 mV off the average.
- What you may notice
- MIL with battery warning, often after standing
- Low cell voltage codes in group C as a follow-up
- Electric range dropping
- Likely causes
- LikelyBalancing transistor in circuit C failed closed
- PossibleEnable or watchdog logic of the module not releasing the switch
- RareLeakage path on the module board
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €300 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.