Powertrain, generic · Hybrid propulsion

P0DD5 Hybrid/EV Battery Cell Balancing Circuit K Stuck On

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

P0DD5 tells that circuit K is discharging its cells without a balancing request. Ford's 2016 hybrid OBD summary links the code to the BECM start-up check: before the contactors close it looks at the six cells of the circuit for 100 ms and fails it when one of them is more than 75 mV away from the average, confirmed on a second power cycle. A switch that conducts by itself can also be caught directly: in Toshiba patent US20130026994A1 the balancing switch is held off while a comparator watches the nodes on both sides of it; if one side sinks below the other, the switch is judged short-circuited. Apart from charge loss, the shorted path heats its resistor all the time. Inactive case: P0DD6.

Likely causes

Shorted balancing switch of group K

Heat damage or contamination bridging the balancing path of K on the board

Driver stage of the monitoring chip holding channel K on

Symptoms

Check engine light at start-up
Group K drops faster than the other cells while parked
Locally higher battery module temperature

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 kbms

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