Powertrain, generic · Hybrid propulsion

P0DDD Hybrid/EV Battery Cell Balancing Circuit M Stuck On

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

P0DDD reports a balancing path of group M that keeps conducting. Ford's 2015 hybrid OBD summary places it in the BECM monitor, judged at power-up before the contactors close: 100 ms, six cells per circuit, more than 75 mV from the average, two consecutive power cycles. A properly working chip should never leave a channel on indefinitely. Infineon's TLE9012DQU, for example, gives each cell its own balancing timer of up to about 3.9 hours and ends balancing on its own once that runs out, or when its over- or undercurrent check trips. If group M still loses charge after such limits, the switch itself is most likely shorted. Expect a low group M after a night of parking. Inactive counterpart: P0DDE.

Likely causes

Shorted balancing switch of group M that no timer can stop

Damaged external balancing transistor on the board for M

High self-discharge cell in group M imitating a stuck switch

Symptoms

Check engine light at start-up
Group M noticeably low after overnight parking
Raised module temperature near group M

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€300–4,500

Time1.5–8 h

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

Parts involved

hv battery cell balancing circuit mbms

References: law.cornell.edu, fordservicecontent.com, infineon.com.