What does code U04B1 mean?

Q: What does code U04B1 mean?

Invalid Data Received From Battery Monitor Module. U04B1 is a communication fault where the vehicle's main control modules have lost valid data from the Battery Monitor Module (BMM), a dedicated sensor or module that tracks battery voltage, current, and state of charge. The computer detects that the messages it expects from the BMM are missing, corrupted, or implausible, so it flags the module as offline or sending invalid data.

DTC codes / U04xx · Invalid data received from a module / U04B1

U04B1Invalid Data Received From Battery Monitor Module

U04B1 is a communication fault where the vehicle's main control modules have lost valid data from the Battery Monitor Module (BMM), a dedicated sensor or module that tracks battery voltage, current, and state of charge. The computer detects that the messages it expects from the BMM are missing, corrupted, or implausible, so it flags the module as offline or sending invalid data.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaInvalid data received from a module

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.