Network, generic

U01A0 Lost Communication With Hybrid/EV Battery Interface Control Module A

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U01A0 names battery interface control module A, the first slave board that reports cell voltages and temperatures of its pack section to the battery controller. GM's 2016-2019 plug-in hybrid tables explain how the code arises: the battery system module talks to eight such boards over a UART daisy chain; once U179C shows that data has stopped, it switches the boards into an internal loopback test and stores the code of the first board it still cannot reach, in 2016 after 5 s above 10.2 V, Type A with MIL on the first trip. Because A sits next to the master, a break ahead of A silences every board in the chain while only A gets named. Audi lists U01A000 for the 2016 A3 Sportback e-tron, which then refuses to make the drive system ready.

Likely causes

Chain wiring or connector between battery controller and module A interrupted
Module A without supply from its cell group or low-voltage feed
Battery interface control module A defective
Chain interface of the battery controller itself faulty

Symptoms

  • Vehicle does not become ready to drive, red hybrid/EV warning
  • MIL on after the first failing trip (GM Type A)
  • Further module codes or U179C stored at the same time

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 acommunication bus

Related codes

U01A1U04A1U033AU0111

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.