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U01A7 Lost Communication With Hybrid/EV Battery Interface Control Module H

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U01A7 refers to battery interface control module H. On packs with exactly eight boards it is the tail of the chain: the GM plug-in hybrid tables for 2016 to 2019 stop at U01A7, and both Audi bulletins (A3 Sportback e-tron 2016, Q5 e 2022 and 2024) list precisely U01A000 to U01A700. Since the master always names the first board it cannot reach, H on its own excludes a break further up; the cause sits in H itself, its supply or the final link leading to it. A fault earlier in the chain shows up as a lower letter, even though H then falls silent as well. GM's 2016 table requires 5 s above 10.2 V and rates the fault Type A, so the MIL lights on the first trip; 2018 to 2019 the time is 4.5 s.

Likely causes

Final chain link from module G to module H interrupted
Battery interface control module H defective
Termination or return line at the end of the chain faulty

Symptoms

  • MIL on the first trip (GM Type A)
  • Electrical system or hybrid warning, power reduced
  • All other module letters report normally

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,000
Time1–8 h

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

Parts involved

hv battery interface module hcommunication bus

Related codes

U01A6U01A8U04A8U0341

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.