Tesla "BMS_w172 Vehicle may not restart" Guide to Fix it

1. Introduction

This is generic alert. There could be many reasons for this alert.

BMS_w172 is an external isolation warning. One of High Voltage components (excluding high voltage battery) has too little resistance between HV Components and chassis ground.  

In most of cases, it could be issue with battery coolant heater, Large Drive Unit, A/C Compressor, Fuse etc. however other HV Components could be faulty. 

The best way would be do isolation testing to find out the exact faulty components.

2. How to Diagnose

This alert could come because of one or more system/feature is disabled/faulty. It need to check additional alerts to find out the cause of this alert.

It could be possible to find out the exact cause via Remote Diagnosis, Service Mode.

2.1 How to check additional alert

It could be possible to find out exact cause via Remote Diagnosis, Service Mode.

2.2 Remote Diagnosis

Please read more details about Remote Diagnosis in another guide (How to do, Cost etc.) Link If you need support. Please Contact Us Phone/Whats App +49(0)15226242038

2.3 Service Mode

It could be possible to do self diagnose via Service Mode.

How to read service alerts in Service Mode

  • On the touchscreen, click Controls > Software
  • Touch and hold the large word "MODEL" for 2 seconds and then release.
  • Enter "service" as access code.
  • After clicking on Service Alerts. You can read service alerts. If there is anything wrong with car. It will show in active alerts.

Please read more details in another guide (How to do diagnosis) Link

In case, If you need support for diagnosis. Please Connect Us.

If you need support. Please send us "Service Alert" Screenshot via Contact or Whats App +49 (0) 15226242038. We will be happy to help you to explain alert and how could be fixed, cost, support for fixing if possible online support or to organize an appointment with independent best affordable workshop.

Depend on alert/fault code, car might need to be repaired/serviced.

3. How to Fix it

Some of alert could come because of software bugs. Some of alert could resolve after restarting the system, software update/reinstall. In some case, car might need hardware repair.

3.1 Restart Touchscreen

Restarting the touchscreen could resolve the issue.

  • Shift car into park.
  • Hold down both scroll buttons on the steering wheel until the touchscreen turns black.
  • Wait approximately 30 seconds for the touchscreen to restart.

 Please read more details in another guide (how to do). Link

3.2 Powering Off the Car

If restarting the touchscreen have not resolved the alert/issue. You could try Powering Off the car.  

  • Please shift car into park
  • On the touchscreen please touch Controls > Safety > Power Off
  • Please wait for at least for two minutes without interacting with the car. Please do not open the doors, touch the brake pedal, touch the touchscreen etc.
  • After 2 minutes, please press the brake pedal or open the door to wake the car (Source Tesla)

3.3 Software Bug

One of reason could be problem with software bug. Updating latest software version might solve the issue. Please read more details in another guide. Link

3.4 Coolant Heater

One of reason could be that coolant heater. Please check more details about possible alert code, how to check, how to repair etc in another guide. Link

3.5. AC Compressor

Please check out more details about about A/C Compressor repair. Link

3.6 Fuse

One of reason could be that fuse is blow up.

3.7 Drive Unit

In case if you have Model S/X with Large Drive Unit. It could be issue with coolant leakage.

Cost

Cost could vary depend on issue, type of workshop, location. If you are looking for online support or affordable independent workshop. Please free to contact us or have a look in Price List

Online Support

In case, if you have any question or need any support/help. Please feel to contact us Contact Us or Whats App +49 (0) 15226242038

Find, compare and Book workshop to Fix it

If are you looking for best workshop who is expert to fix such issue with good price. Please contact us we will be happy to organize an appointment with workshop or find, compare and book best workshop in Workshop Locator

Book an Appointment

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Buy New/Used Spare Parts

If you would like to buy spare parts. Please have a look in our catalog or Contact Us Phone/Whats App +49(0)15226242038

Alert Code

Possible alert code

1. BMS_w172

BMS_w172_SW_Drive_Iso_Warning

The battery management system (BMS) has detected low isolation conditions during multiple drive cycles.

In case if you have Model S/X and got BMS_w172 together with BMS_u008. In most cases, it could be issue with Coolant Heater, Compressor, Fuse

Please send us "Service Alert" Screenshot via Contact or Whats App +49 (0) 15226242038. We will be happy to help to fix alert.

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Frequently Asked Questions (FAQs)

 

 


 

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Disclaimer: Tesla, Inc. was not involved in the creation of this document. Tesla did not provide us any info. Tesla did not edit, review or authorize us. We gather this information from Tesla official website and other resources.

Note: It is your responsibility to double check and confirm that the procedures/info mentioned in this blog are applicable to your specific car before performing them. Please contact us or our workshop partner to make sure/confirm. We will be happy to help you.