Vehicle May Not Restart — HV Isolation Fault While Driving or Charging
The TESLA-BMS_A035 (Tesla BMS (Battery Management System)) EV fault code means: Vehicle May Not Restart — HV Isolation Fault While Driving or Charging. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- expert
- Estimated cost
- Diagnosed and quoted by Tesla service; isolation faults range from moisture/component issues to major pack work. Battery-related repairs may be covered by the battery and drive unit warranty — check your coverage.
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Common Symptoms
- Alert on the touchscreen: "Vehicle may not restart — Service is required"
- Vehicle may be unable to charge, drive, or support other vehicle systems
- May appear during driving or while charging
- May appear alongside other high-voltage or BMS alerts
Probable Causes (Ranked by Likelihood)
- Reduced electrical isolation detected in the high-voltage system while driving or charging (Tesla's official description); the high-voltage system is electrically isolated from the vehicle frame for safety, and the vehicle limits functions when isolation falls below acceptable levels Likely
Step-by-Step Diagnostic Procedure
This is a high-voltage electrical-safety alert: the insulation between the high-voltage system and the vehicle frame has degraded below Tesla's acceptable level, detected while driving or charging.
Per Tesla's official guidance, the vehicle may be unable to charge, drive, or support other systems, and you should schedule service if the alert persists across drives.
Limit driving to what's necessary to get the vehicle somewhere serviceable — it may not restart once parked.
High-voltage isolation diagnosis is Tesla-service-only work — never attempt to inspect or repair the high-voltage system yourself.
Frequently Asked Questions
What does BMS_a035 mean on a Tesla?
Tesla's official meaning: the vehicle detected reduced electrical isolation in the high-voltage system while driving or charging. The high-voltage system is electrically isolated from the vehicle frame for safety; when that isolation falls below acceptable levels, the vehicle limits certain functions and may be unable to charge, drive, or support other systems.
Can I keep driving with BMS_a035?
Treat it as a get-to-service alert, not a keep-commuting alert. Tesla's text warns the vehicle may not restart and says to schedule service if the alert persists. Limit driving to what's necessary and get it inspected.
Is BMS_a035 the same as BMS_a151?
They're closely related — both indicate reduced high-voltage isolation detected while driving or charging. BMS_a151's official text additionally says not to attempt charging and to contact Roadside Assistance if you notice unusual smells, sounds, or visible damage near the battery.
Sources
This page is built from documented references. Verify against your own service info before repair work.
- Tesla Model 3 Owner's Manual — Troubleshooting Alerts (official Tesla alert text for BMS_a035)
- Tesla Model Y Owner's Manual — Troubleshooting Alerts (confirms BMS_a035 is documented across models)
- Tesla firmware alert reference (core-hacked/tesla-alerts-dictionary): bms_a035
- Tessie Tesla alert statistics