Powertrain, generic · Hybrid propulsion

P0DB6 Hybrid/EV Battery Cell Balancing Circuit C Stuck Off

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P0DB6 says that the bleed function of group C does not respond: commanded on, circuit C stays dead. In LG Chem's US20110285539A1 such a case shows up because a test capacitor charged to cell voltage is not emptied through the balancing path and keeps a high residual voltage. Typical culprits are an open resistor, a transistor that no longer conducts or a broken cell tap. While driving there is little to feel; the effect is that group C cannot be trimmed, so the strongest cell there caps every full charge. CARB 13 CCR 1968.2 demands detection of this. Ford documents P0DB6 in the 2018 OBD summary for its hybrids, one of fourteen balancing circuits there; a 75 mV spread inside the six-cell group, seen on two consecutive power cycles before the contactors close, triggers it.

Likely causes

Bleed resistor of circuit C open
Balancing transistor of circuit C not conducting
Broken cell tap or weld in group C

Symptoms

  • MIL with battery warning
  • Shorter charging sessions and lower usable capacity

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 cbms

Related codes

P0DABP0DB4P0DB5P0DB7P0DE7

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