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U01BD Lost Communication With DC/DC Converter Control Module C

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Electrified cars may carry several DC/DC converters, each turning one direct voltage into another: the main unit supplies the 12 V system from the traction battery, others feed 48 V consumers or single heavy loads. Vitesco, for instance, added a dedicated DC/DC converter in high-voltage hybrids purely to power the electrically heated catalyst. U01BD means the third converter module, C, has stopped communicating, so the hybrid or vehicle controller loses its status, voltage and current readings. No manufacturer documents this code publicly. Ford's 2014 OBD list carries the sibling U0298 for converter A without a MIL flag, a hint that such codes stay non-MIL unless the converter serves an emissions function. Expect an electrical system warning and load shedding; U0298 and U0299 cover A and B.

Likely causes

Low-voltage supply, wake-up line or connector of converter C faulty
Converter shut down by an open high-voltage interlock or contactor state
DC/DC converter C control electronics faulty

Symptoms

  • Electrical system or 12 V warning
  • Comfort loads switched off to save energy

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€0–2,000
Time0.5–4 h

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

Parts involved

dcdc converter module ccan bus

Related codes

U0298U0299U0599U059A

References: en.wikipedia.org, electronics-journal.com, performanceparts.ford.com.