Battery Brick Over-Voltage — a Cell Group Is Above the Maximum Acceptable Voltage
The TESLA-BMS_W017 (Tesla BMS (Battery Management System)) EV fault code means: Battery Brick Over-Voltage — a Cell Group Is Above the Maximum Acceptable Voltage. This is a critical severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- professional
- Estimated cost
- Diagnosed by Tesla or a qualified high-voltage specialist. Cost depends on whether a cell group or a sensing circuit is at fault, and pack-level repair on these model years ranges widely. Confirm warranty coverage first.
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Common Symptoms
- Touchscreen shows "Service is required" together with "PULL OVER SAFELY"
- The car will not charge
- The car will not drive, or stops being able to
- The 12V/low-voltage system loses support, which can take down lights, screens and door handles
Probable Causes (Ranked by Likelihood)
- A "brick" — Tesla's term for a group of cells wired in parallel — is reporting a voltage above the maximum acceptable cell voltage, and the battery management system has acted on it. High
- An ageing or damaged cell group in the high-voltage pack. This alert is scoped to Model S 2012-2020 and Model X 2015-2020, which are the older pack designs. Medium
- A sensing or measurement fault reporting a voltage the brick is not actually at. Only a pack-level diagnosis can separate this from a genuine over-voltage. Low
Frequently Asked Questions
What does BMS_w017 mean on a Tesla?
Its firmware name is BMS_w017_SW_Brick_OV. The battery management system has detected that a brick — a parallel group of cells in the high-voltage pack — is reporting a voltage above the maximum acceptable cell voltage.
Can I keep driving with BMS_w017?
No. The alert is accompanied by "PULL OVER SAFELY", and the stated impact is an inability to charge, drive, or support the low-voltage system. Stop safely and arrange transport rather than driving on.
Which Teslas get BMS_w017?
It is listed for Model S 2012-2020 and Model X 2015-2020 — the older pack designs. It is not listed for Model 3, Model Y or Cybertruck.
Will BMS_w017 clear by itself?
It clears when the BMS sees every brick back at an acceptable cell voltage. That is a description of the clear condition, not a repair strategy — the underlying pack condition still needs diagnosis.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
Do what the car says first: PULL OVER SAFELY. This alert carries that instruction, and the stated impact includes losing the ability to support the low-voltage system — which is what runs your lights and door handles.
Do not keep driving to "get it home". The alert reports an inability to charge, drive, or support the LV system.
Do not attempt to charge the vehicle while this is active.
Arrange transport rather than a drive to service. Tesla roadside assistance is reachable from the app.
High-voltage pack work is not DIY at any skill level. The pack stores lethal energy and requires isolation procedures and equipment.
Check battery warranty status before authorising work — the 8-year battery and drive unit warranty has mileage caps that vary by model and year, and these are the model years where that boundary matters.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- Tessie alert explorerBMS_w017_SW_Brick_OV (description, cause, impact, clear condition and applicable models)third-party Tesla alert reference with owner-telemetry frequency — not an official Tesla document
- Tesla firmware alert reference (core-hacked/tesla-alerts-dictionary): BMS_w017_SW_Brick_OVcommunity-maintained dictionary, not an official manufacturer document
Commonly Affected Vehicles
- Tesla Model S (2012-2020)
- Tesla Model X (2015-2020)
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