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U01B0 Lost Communication With Battery Monitor Module

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

U01B0 says the 12 V battery monitor module, a small sensor on the negative battery post that reports voltage, current, temperature and state of charge, has stopped replying. GM polls it over LIN: its 2018 engine tables (18OBDG03A) flag the code once frame 18_C02 has been absent for 1.25 s, the 2025 body controller tables (25OBDG04A) after 12.6 s; both rate it Type B, two trips. GM bulletins 15-NA-087 and 22-NA-214 list it with a disabled stop/start system and a lit MIL, have the battery and LIN wiring checked first and the sensor swapped last; afterwards it must relearn, which a parasitic drain above about 250 mA blocks. Volkswagen lists U01B000 with MIL in the engine controller of the 2024 Atlas. U04B1 is the invalid-data partner.

Likely causes

Loose, corroded or damaged LIN connector or wire at the battery sensor
Weak or deeply discharged 12 V battery
Battery monitor sensor faulty (GM replaces it after the checks)
Parasitic drain preventing the sensor relearn

Symptoms

  • Stop/start system disabled, message in the driver display
  • MIL on
  • Battery state of charge shown wrongly or battery saver functions inactive

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–300
Time0.3–2 h

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

Parts involved

battery monitor modulelin bus

Related codes

U04B1U01BFU0140

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