BMS-F123
BMS_f123_SW_Internal_Isolation
Also written as BMS_F123 / BMS F123 / BMS_f123_SW_Internal_Isolation / bms_f123_sw_internal_isolation
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-F123 mean?
Tesla fault code in the Battery Management System (BMS) module. This alert points to a high voltage (HV) battery internal isolation breakdown detected. This condition is concerning and should be should be addressed rapidly and thoroughly. Thresholds: BMS_a123 will trip if the isolation is below 500 Ohm/Volt or 192 Kohms at 385V and the contactors are open. The alert will clear if the isolation goes over 1000 ohm/volt and the contactors are open.
Original Description
This alert points to a high voltage (HV) battery internal isolation breakdown detected. This condition is concerning and should be should be addressed rapidly and thoroughly. Thresholds: BMS_a123 will trip if the isolation is below 500 Ohm/Volt or 192 Kohms at 385V and the contactors are open. The alert will clear if the isolation goes over 1000 ohm/volt and the contactors are open.
Affected Tesla Models
What You May Notice
- Red warning light on dashboard: This alert points to a high voltage (HV) battery internal isolation breakdown detected. This condition is concerning and
- Vehicle may refuse to drive or charge until the fault is cleared
- Sudden power reduction or shutdown may occur while driving
How to Diagnose and Resolve
- 1 Stop driving immediately and move to a safe location
- 2 Do not attempt to charge the vehicle — active fault: "This alert points to a high voltage (HV) battery internal is"
- 3 Call Tesla Roadside Assistance (+1-877-798-3752) for a flatbed tow
- 4 At the Service Center, Tesla technicians will inspect the HV battery pack and BMS firmware
Severity Notes
BMS-F123 is classified as a Fault, indicating a critical issue in the Battery Management System system. Do not continue driving and contact Tesla Service immediately.