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U059A Invalid Data Received From DC/DC Converter Control Module B

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Converter B is a second DC/DC unit, used when one voltage support stage is not enough or when separate networks need their own supply. FCA is the only maker that names it publicly: in powertrain module updates for the 2019 Jeep Cherokee with the 3.2-litre V6 and engine stop-start (18-023-19 and follow-ups such as 18-020-21), the PCM lists both U0599 and U059A for invalid data from DC-to-DC converters A and B, plus U0299 for lost contact with converter 2. The customer complaint in those bulletins is a MIL and an engine that sometimes fails to restart after a stop-start event, and the fix is new PCM software rather than a new converter. A failing second converter mostly shows up as start-stop being withdrawn or electronics resetting during restarts.

Likely causes

Powertrain controller software evaluating converter B data incorrectly (FCA 18-023-19)
Second DC/DC converter faulty
Wiring or ground connection of converter B poor

Symptoms

  • Check engine light
  • Engine does not restart after a stop-start event
  • Stop-start function withdrawn

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–900
Time0.3–2 h

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

Parts involved

dc dc converter module b

Related codes

U0299U0599

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.