BMS-A109
BMS_a109_HW_BMB_Mute_Status_Mismatch
Also written as BMS_A109 / BMS A109 / BMS_a109_HW_BMB_Mute_Status_Mismatch / bms_a109_hw_bmb_mute_status_mismatch
Why does the exact Tesla alert ID matter?
Record the exact alert ID, including underscores, suffixes, and companion alerts. Tesla alerts that look similar can point to different modules, timestamps, and service procedures.
What does BMS-A109 mean?
Tesla alert code in the Battery Management System (BMS) module. A BMB device has a MUTE status that does not align with the MUTE/UNMUTE command sent by the BMS MUTE is disabled for any device while balancing, or otherwise enabled for any device MUTE is enabled for all devices while balancing, or otherwise disabled for all devices Bleeding bricks that do not MUTE during balancing can impact SOC estimation
Original Description
A BMB device has a MUTE status that does not align with the MUTE/UNMUTE command sent by the BMS MUTE is disabled for any device while balancing, or otherwise enabled for any device MUTE is enabled for all devices while balancing, or otherwise disabled for all devices Bleeding bricks that do not MUTE during balancing can impact SOC estimation
Affected Tesla Models
What You May Notice
- BMS-A109 may appear with another Tesla alert in the Battery Management System (BMS) system.
- The vehicle may limit charging, driving, comfort, or safety features depending on the active alerts.
- The alert may clear after sleep, but recurring alerts should be treated as service-relevant.
How to Diagnose and Resolve
- 1 Reboot the vehicle (hold both scroll wheels for 10 seconds)
- 2 Check the Tesla app for any pending software updates
- 3 Monitor the alert over 1–2 charge cycles; schedule service if it recurs
Severity Notes
BMS-A109 is an Alert in the Battery Management System system. Confirm the vehicle screen and Tesla app show no driving or charging restrictions, and schedule service if the alert returns.