U04B1: Invalid Data Received From Battery Monitor Module

What it means

A control module received invalid data from the battery monitor module. The code identifies a data validity fault; the specific affected function depends on the vehicle.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

The battery monitor module tracks battery-related information and shares it with other control modules over the vehicle network. U04B1 sets when a receiving module judges data from the battery monitor module invalid; it does not by itself identify which monitoring or charging function is affected.

Common causes

Most likely first.

1. Fault in the transmitting module
2. Network wiring or connector fault
3. Module power or ground fault
4. Software or configuration mismatch

Symptoms

• Battery monitoring or charging functions may be affected
• Related communication codes or system warnings may appear

How to diagnose it

1. Save freeze-frame data and scan all modules for battery, charging, and communication codes to check whether this is an isolated message fault or part of a broader power issue.
2. Review live data and code status for battery monitor messages to identify which readings are missing or marked invalid and whether the fault is intermittent.
3. Inspect the battery monitor module's accessible connector, its wiring, and nearby battery connections for looseness, corrosion, damage, or poor contact.
4. Check the module's power and ground circuits under load against the manufacturer's specification, since voltage or ground problems can disrupt reporting.
5. Test the network wiring between the battery monitor module and other modules using the vehicle wiring information and manufacturer's procedures.
6. If wiring and supply are sound, verify module software and configuration, then test the battery monitor module for an internal fault.

Common fixes

• Secure the battery monitor module connector and clean or repair corroded terminals.
• Repair damaged network wiring or a poor battery monitor module connection.
• Repair a faulty power or ground connection to the battery monitor module.
• Correct an applicable software or configuration mismatch using the manufacturer's approved procedure.
• Replace or repair the battery monitor module if testing confirms it is faulty.

Can I keep driving?

A communication fault may affect battery monitoring or charging functions, even if the vehicle currently drives normally. Limit unnecessary electrical loads if charging warnings appear, and address the fault promptly to reduce the risk of a discharged battery or loss of related functions.