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U0344 Software Incompatibility With Hybrid/EV Battery Interface Control Module K

Check engine lightUsually off
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Eleven boards or more are found in GM's Ultium packs: according to Wikipedia the Cadillac Lyriq carries twelve modules and the Hummer EV two layers of twelve, and the battery management works wirelessly. GM's service update N232401570 of October 2025 shows that master software decides whether such a unit is accepted: on 2023–2024 Lyriq and BrightDrop, 2024 Blazer EV and Silverado EV and 2022–2024 Hummer EV, the battery energy control module could stay stuck in its start-up commissioning because one cell monitoring unit was offline. The fix is a reprogrammed control module, by the dealer or over the air, without parts. GM does not say which codes appear. U01AA and U04AB cover K's silence and bad data.

Likely causes

Battery controller software does not accept the monitoring unit
Released software update for the battery controller not yet installed
Monitoring unit K replaced and not registered

Symptoms

  • Vehicle does not become ready after switching on
  • Battery or propulsion warning
  • Charging may be refused

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€0–500
Time0.2–2 h

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

Parts involved

hv battery interface module k

Related codes

U01AAU04ABU0343U0345

References: static.nhtsa.gov, en.wikipedia.org.