U04B1Invalid Data Received From Battery Monitor Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- 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.
- What you may notice
- Check engine light (GM Type B, after two trips)
- Start-stop disabled or charging strategy of the generator changed
- Likely causes
- LikelyBody control module configuration lost or mismatched after reprogramming (Alfa Romeo)
- PossibleIntelligent battery sensor on the negative terminal faulty
- PossibleLIN lead or plug at the battery sensor damaged or corroded
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.