Network, generic

U04B1 Invalid Data Received From Battery Monitor Module

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Despite its place after the high-voltage interface series, U04B1 usually concerns the 12 V side: in GM's 2024 OBD table 24OBDG07 the battery monitor module is the intelligent battery sensor on the 12 V battery, read by the body control module over LIN. GM sets U04B1 when the alive rolling counts of the sensor's signals, among them charged and discharged amp-hours, state of charge, temperature and crank data, are wrong in 8 of 10 samples, polled every 250 ms, with the car in run, above 11 V and at least 5 s after power-up; Type B, two trips. Alfa Romeo reported U04B1-00 in the PCM of 2017–2019 Giulia and Stelvio after a module flash and cleared it with a BCM configuration restore. U01B0 means the sensor is silent.

Likely causes

Body control module configuration lost or mismatched after reprogramming (Alfa Romeo)
Intelligent battery sensor on the negative terminal faulty
LIN lead or plug at the battery sensor damaged or corroded

Symptoms

  • Check engine light (GM Type B, after two trips)
  • Start-stop disabled or charging strategy of the generator changed

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–300
Time0.3–1.5 h

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

Parts involved

battery monitor module

Related codes

U01B0U04C0

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