VCFRONT_a402_LVBatteryCannotSupportVehicle
Electrical system backup power is unavailable
What does the VCFRONT_a402_LVBatteryCannotSupportVehicle alert mean?
The vehicle controller has detected a condition where the low voltage (LV) battery is unable to support vehicle electrical systems. The vehicle is likely to shut down if high voltage (HV) battery support for vehicle electrical systems via the power conversion system (PCS) is lost, so the HV system will remain energized to continue supplying electrical power to the vehicle until the alert clears.
What you'll see in your Tesla
- Electrical system backup power is unavailable
- Vehicle will consume more energy while idle
What triggers it
The LV battery is disconnected or showing degraded functionality, the LV battery internal protection transistor (MOSFET) is detected open, or the reverse battery eFuse has tripped (circuit is open).
When it clears
The vehicle controller no longer detects a condition where the LV battery is unable to support vehicle electrical systems. May include reconnecting or replacing the LV battery, the LV battery internal protection transistor (MOSFET) being detected closed, or reverse battery eFuse no longer tripped (circuit closed again).
Potential impact
The LV battery is unable to support vehicle electrical systems. The high voltage (HV) system will remain energized to continue supplying electrical power to the vehicle while the LV battery is unavailable. This may result in greater range loss than expected, increased HV system energy consumption when the vehicle is idle, and prevent the vehicle from sleeping.
Affected models
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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.