--- title: "Tesla BMS_a035 / BMS_a151: Vehicle May Not Restart Fix | EV Fix Guide" description: "BMS_a035 and BMS_a151 mean the car detected reduced electrical isolation between the high-voltage system and the car body. The car may refuse to charge or drive. Common causes are water getting into a high-voltage connector or component, a damaged cable, or an internal battery fault. Tesla Service: $0. Independent: $300 - $2,500. Why it is not DIY and where to get it fixed." canonical: https://evfixguide.com/guides/bms-a035-a151-isolation-may-not-restart lang: en last_updated: 2026-10-24 --- [Tesla Model 3](https://evfixguide.com/models/model-3) · [Tesla Model Y](https://evfixguide.com/models/model-y) · [Tesla Model S](https://evfixguide.com/models/model-s) · [Tesla Model X](https://evfixguide.com/models/model-x) Battery & Low-Voltage Professional repair only # Tesla BMS_a035 / BMS_a151: Vehicle May Not Restart Fix By the EV Fix Guide editorial team · Updated October 24, 2026 · [How we estimate costs](https://evfixguide.com/about#how-we-estimate-costs) ## Quick answer BMS_a035 and BMS_a151 mean the car detected reduced electrical isolation between the high-voltage system and the car body. The car may refuse to charge or drive. Common causes are water getting into a high-voltage connector or component, a damaged cable, or an internal battery fault. At a Tesla Service Center this typically costs **$0 (Under warranty) / $300 - $3,000 (Component repair) / $12,000 - $20,000 (Pack replacement)**. An independent shop charges about **$300 - $2,500 (Isolation diagnosis and component repair)** — potential savings of **30% - 80%**. **Do not attempt this at home.** ![BMS_a035 / BMS_a151: Vehicle May Not Restart - High Voltage Isolation Fault](https://evfixguide.com/assets/images/battery-bench.jpg) ## Symptoms - 'Vehicle may not restart - Service is required' alert with code BMS_a035 or BMS_a151 - Charging refuses to start or stops - Often appears after heavy rain, a car wash, deep puddles or underbody damage - May clear on its own and come back later ## Repair cost: Tesla vs independent shop vs DIY | Option | Typical cost (USD) | | --- | --- | | Tesla Service Center | $0 (Under warranty) / $300 - $3,000 (Component repair) / $12,000 - $20,000 (Pack replacement) | | Independent shop | $300 - $2,500 (Isolation diagnosis and component repair) | | DIY | Not possible at home (High-voltage hazard) | | Potential savings | 30% - 80% | Ranges are US estimates compiled from owner reports and shop quotes; prices vary by region, model year and parts availability. Report your price. ## Can an independent shop fix it? Isolation faults need high-voltage diagnosis to find which component is leaking (pack, heater, compressor, charger, cables). Inside the battery warranty go to Tesla. Out of warranty, independent EV high-voltage specialists can test each component and replace only the faulty one, which is often far cheaper than a new pack. [Get matched with an independent shop →](https://evfixguide.com/?shop=bms-a035-a151-isolation-may-not-restart#find-shop-section) ## How professionals repair it **Safety warning:** This is a high-voltage safety fault. Do not open any orange cables or components. Tesla says not to charge the car with BMS_a151 active, and to stop using it if you smell, hear or see anything unusual near the battery. ### Tools a shop uses - Tesla app (to log alerts and book service) - Notes on weather and what happened before the alert appeared ### Steps 1. Do not try to charge the car while BMS_a151 is active; Tesla's manual says so explicitly. 2. If you notice smoke, a burning or sweet chemical smell, hissing or visible damage near the battery, leave the car, move away and call Roadside Assistance. 3. Write down when the alert appeared: after rain, a car wash, a flooded road, or hitting debris are all useful clues for the technician. 4. If the alert clears and does not return over the next few drives, keep an eye on it but you may not need service. 5. If it persists, book service. Check your 8-year battery and drive unit warranty first. 6. Out of warranty, ask an independent EV specialist for an isolation test that names the faulty component before accepting a pack replacement quote. **Pro tip:** Isolation faults are frequently caused by moisture in a single connector or component, not a dead battery. A proper component-by-component test is what separates a few-hundred-dollar repair from a five-figure one. ## Frequently asked questions ### How much does it cost to fix a BMS_a035 or BMS_a151 isolation alert on a Tesla? Tesla Service Center: $0 (Under warranty) / $300 - $3,000 (Component repair) / $12,000 - $20,000 (Pack replacement). Independent shop: $300 - $2,500 (Isolation diagnosis and component repair). DIY: Not possible at home (High-voltage hazard). Typical savings versus the service center: 30% - 80%. ### Can I fix a BMS_a035 or BMS_a151 isolation alert myself? No, this is not a safe DIY job. This is a high-voltage safety fault. Do not open any orange cables or components. Tesla says not to charge the car with BMS_a151 active, and to stop using it if you smell, hear or see anything unusual near the battery. ### Can an independent shop fix a BMS_a035 or BMS_a151 isolation alert instead of Tesla? Isolation faults need high-voltage diagnosis to find which component is leaking (pack, heater, compressor, charger, cables). Inside the battery warranty go to Tesla. Out of warranty, independent EV high-voltage specialists can test each component and replace only the faulty one, which is often far cheaper than a new pack. ### Which Tesla models are affected by a BMS_a035 or BMS_a151 isolation alert? This issue is reported on the Tesla Model 3, Model Y, Model S and Model X. ## Related guides - [Tesla 12V / 16V Battery Replacement: Cost & DIY Guide — Independent: $100 - $150](https://evfixguide.com/guides/12v-16v-low-voltage-battery) - [Tesla Charge Port Door Stuck or Won’t Open: Fix & Cost — Independent: $120 - $200](https://evfixguide.com/guides/charge-port-door-stuck) - [Tesla BMS_u029 / BMS_f107 Battery Fault: Repair Cost — Independent: $1,800 - $3,500](https://evfixguide.com/guides/bms-u029-battery-isolation) - [Tesla Pyrofuse Failure: Symptoms & Replacement Cost — Independent: $190 - $320](https://evfixguide.com/guides/pyrofuse-high-voltage-fuse) - [Tesla Frunk Won’t Open (Dead 12V): Model 3/Y Fix — Independent: $50 - $150](https://evfixguide.com/guides/frunk-dead-12v-battery) - [Tesla VCFRONT_a180: Electrical System Power Reduced Fix — Independent: $100 - $300](https://evfixguide.com/guides/vcfront-a180-electrical-power-reduced) This guide is for information only. High-voltage components (orange cables) can be lethal — leave them to trained technicians. Not affiliated with Tesla, Inc.