Network, generic

U01AD Lost Communication With Hybrid/EV Battery Interface Control Module N

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U01AD names battery interface control module N, the fourteenth board in a monitoring chain. No manufacturer documents this code publicly, and even GM's broad fault bundle stops at M. The reason such codes exist at all lies in CARB's rule 1968.2, section (e)(15.2.3): hybrid OBD systems must supervise the electronic inputs of the energy storage system, such as cell voltage and temperature sensing, and store separate codes that pinpoint the smallest unit replaceable in service. A pack built from many separately replaceable monitoring boards thus needs one code per board. In a daisy chain of the kind GM describes, a stored U01AD would mean that the boards up to M still answer and N is the first one lost. Neighbouring codes for N are U04AE and U0347.

Likely causes

Chain connection between module M and module N interrupted
Battery interface control module N defective

Symptoms

  • Battery warning, power and charging limited
  • Cell data of one pack section missing in the scan tool

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,500
Time1–10 h

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

Parts involved

hv battery interface module ncommunication bus

Related codes

U01ACU01AEU04AEU0347

References: law.cornell.edu, gsi.ext.gm.com, en.wikipedia.org.