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U04A8 Invalid Data Received From Hybrid/EV Battery Interface Control Module H

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U04A8 is the invalid-data code for interface module H. In GM's 2016 hybrid table 16OBDG02, H is the last of eight boards that the battery systems module reaches through a daisy chain; a pack of that design needs no higher letter. GM explains that a break anywhere in such a chain cuts off every board behind it, so lost contact is reported for the first board that cannot be recovered. An invalid-data code is different: if only H's frames fail the checks while A to G pass, the cause is more likely local to H, its connector or its cell inputs. No manufacturer documents U04A8 publicly. U01A7 means H is silent, U0341 a software mismatch. The driver sees a hybrid warning and may lose power.

Likely causes

Interface control module H internally faulty
Connector or lead fault at the last board of the chain
Faulty cell input on board H producing impossible values

Symptoms

  • Hybrid system warning, MIL on plug-in hybrids
  • Reduced propulsion power

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–3,000
Time1.5–8 h

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

Parts involved

hv battery interface module h

Related codes

U01A7U0341U04A7U04A9

References: gsi.ext.gm.com, en.wikipedia.org.