What happened
The car is a 2020 US-market Tesla Model Y (VIN 5YJYGDEE9LF021378) listed on av.by. Before the test drive, the main screen showed a BMS_a066 alert: "Maximum charge level and range may be reduced. OK to drive — Schedule service soon."
Per a chat member who was considering the purchase, the seller assured them "it's all fine" and that it just needs a "discharge / slow-charge cycle" at a Tesla service.
What BMS_a066 means
BMS = Battery Management System. Code a066 means the system has detected a condition internal to the high-voltage battery that limits performance: maximum charge level and range drop. Tesla explicitly states that service is required to restore full performance.
In practice this is often cell/module imbalance. A "cycle" sometimes helps with mild imbalance — but if the code persists, that calls for serious diagnostics, not a shrug. Worst case it is a module or pack replacement costing thousands of dollars. More on what drives imbalance in our separate write-up (links below).
Water signs: the river video
Beyond the battery alert, there is a public video (link below) of this car fording a river. We are not claiming the car is legally "flood-damaged" — but driving an EV through deep water is a strong reason to inspect it carefully for moisture traces, connector corrosion and the state of the high-voltage components.
For an EV, water in the wrong places is a far more serious and hidden risk than for a combustion car: corrosion of HV connectors and controllers does not show up immediately.
Why this matters to a buyer
Battery imbalance and possible water exposure are two independent red flags on one car. Either can mean an expensive post-purchase repair: a battery module, corrosion, HV-safety issues.
Meanwhile, per chat members, the seller downplays the problem and pushes back on anyone who raises it. The decision is yours — but go into the deal with open eyes and an independent inspection, not on a "it's all fine, just buy it."
How to protect yourself
— Open Service Mode and check the battery warnings/errors section; ask for the BMS_a066 history. — Get an independent pre-purchase inspection at a Tesla-focused shop (see our services list). — Check the car for water traces: damp smell, connector corrosion, condensation/haze in the head- and tail-lights, silt in hidden cavities. — Verify the VIN and history against public databases. — Don't rush under seller pressure. The full checklist is in our used-Tesla buying guide (links below).
Our position & right of reply
This write-up is based on public materials (the av.by listing, the YouTube video, the screen photo) and reports from the TESLA Belarus community. The verifiable facts are public: anyone can see the on-screen error, the listing and the video. The value judgments ("a minor thing", "dismisses doubters") belong to chat members.
If tesla-cars.by has documentary evidence to the contrary — e.g. a service report that the battery is healthy, or confirmation the car never contacted water — write to us and we will add your statement or correct the material.