BMS family
BMS_a164_SW_Uncontrolled_Regen
Unable to drive
What does the BMS_a164_SW_Uncontrolled_Regen alert mean?
The battery management system (BMS) detects an uncontrolled regen event.
What you'll see in your Tesla
- Unable to drive
- PULL OVER SAFELY
What triggers it
The BMS detects regen power above the maximum threshold while in drive.
When it clears
The BMS detects regen power within the threshold while in drive.
Potential impact
Inability to charge, drive, or support the low voltage (LV) system
Affected models
Model 3 2017-2023
Model 3 2024+
Model S 2021+
Model X 2021+
Model Y
Model Y 2025+
Track your Tesla's alerts automatically
Alerts like this reach MyTeslaMate through your car's Tesla telemetry API. MyTeslaMate logs every alert your Tesla reports and turns it into readable history and real-time notifications — hosted TeslaMate with no server to run.