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U0340 Software Incompatibility With Hybrid/EV Battery Interface Control Module G

Check engine lightUsually off
EmissionsRelevant
Drive cycleNot required
Limp modePossible

G is the seventh board, a position GM's 2016–2019 plug-in hybrids really have: table 16OBDG02 describes eight interface modules on a UART daisy chain to the battery system module. That table publishes lost-contact and processor tests for every board, yet it holds no counterpart to the P1EB1 version check of the older VITM design and no U0340. For G, GM thus documents silence (U01A6), not a software conflict. The older four-board design is stricter: P1F06 to P1F09 make each slave return a key value computed by a seed-and-key algorithm and fail it when wrong values persist for 1 s within a 1.4 s window, Type B in the 2015 table. U04A7 is the invalid-data code for G.

Likely causes

Seventh board replaced by a unit with another software level
Battery system module reflashed without the boards being brought along
Disturbed daisy-chain link garbles the version data of board G

Symptoms

  • Hybrid warning, MIL possible depending on the maker
  • Electric mode limited or unavailable
  • Other battery diagnostics paused while the code is active

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–900
Time0.5–3 h

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

Parts involved

hv battery interface module g

Related codes

U01A6U04A7U033FU0341

References: gsi.ext.gm.com, gsi.ext.gm.com.