BMS_a027 error

[Qasim]

I have 2021 Model 3, after Recent update to 2022.28.1 I had this BMS_a027 fault. It says High voltage isolation dropped under threshold many drive sessions. I’ve seen these posts in Tesla Facebook groups which were the same issues after recent update to 2022.28.1
Strangely all post disease from Facebook now but I’ve screenshot.

 

[tstolze]

Have you had any motor/inverter replacements in your car?

I received these errors this morning after a software update to 2022.36.20 last night.
Had my front inverter replaced 2nd week of October.
Service requested, I will update when I have answers.

 

[Dzhama Omarov]

How do you clear the errors?

I did it via Tesla toolbox 3, takes less than a minute

 

[Dzhama Omarov]

I received these errors this morning after a software update to 2022.36.20 last night.
Had my front inverter replaced 2nd week of October.
Service requested, I will update when I have answers.

The may just forgot to delete the errors

 

[Dzhama Omarov]

I haven't. It's just surprising that it comes up right after a software update.

I have a service appointment on Friday. They said this issue cannot be diagnosed with a mobile appointment. But since I have to drive 90 mins on a highway to get to it, I'm not sure how fast I can go on "limited power". Hopefully fast enough for highway driving.

I guess the error says “ok to drive”, so you should be able to get to SC with no problems

 

[Dzhama Omarov]

I did it via Tesla toolbox 3, takes less than a minute

Forgot to tell, you’ll need special Ethernet-Tesla cable, you can find one on Amazon

 

[tstolze]

I received these errors this morning after a software update to 2022.36.20 last night.
Had my front inverter replaced 2nd week of October.
Service requested, I will update when I have answers.

Service center says these codes are leftover from an inverter replacement last month that are being displayed with the latest software update, they will clear them next Tuesday.
Strange driving with no regen and reduced acceleration.

 

[Tiesla00]

Service center says these codes are leftover from an inverter replacement last month that are being displayed with the latest software update, they will clear them next Tuesday.
Strange driving with no regen and reduced acceleration.

Thanks for posting this. I just had the same errors and driving experience after the software update. I too had an inverter replaced mid-October so hopefully this is the same case for me. Going to schedule service now.

 

[floatplane]

I got the pair of alerts Wednesday after updating software to 2022.36.20 (FSD Beta 10.69.3.1) overnight but have never had the inverter replaced, as others report, and no other maintenance in the past 3 years beyond HW3 install.

Strangely the nav forgot my home address too and said it wasn’t set.

 

[Dzhama Omarov]

Service center says these codes are leftover from an inverter replacement last month that are being displayed with the latest software update, they will clear them next Tuesday.
Strange driving with no regen and reduced acceleration.

Congrats! Enjoy the full power of the car

 

[yrethguad]

I think I'm in the same boat. Since the 2022.36.20 update I've had the same errors. I had the rear drive unit replaced in August, which I believe would have included the inverter. I miss how my car was. My SC appointment is Dec 21...... Really sucks using brakes like a troglodyte. I was really concerned too since my basic warranty just ended... And this car's parts are expensive... I've been searching for days, and I'm glad I finally found this thread, so thank you.

 

[Dzhama Omarov]

I think I'm in the same boat. Since the 2022.36.20 update I've had the same errors. I had the rear drive unit replaced in August, which I believe would have included the inverter. I miss how my car was. My SC appointment is Dec 21...... Really sucks using brakes like a troglodyte. I was really concerned too since my basic warranty just ended... And this car's parts are expensive... I've been searching for days, and I'm glad I finally found this thread, so thank you.

No worries, how much would the appointment cost? I saw someone posted approximately 1000$ for the visit to SC. If it’s your case, maybe it’s better to buy Toolbox subscription and do it yourself. Just a thought)

 

[yrethguad]

No worries, how much would the appointment cost? I saw someone posted approximately 1000$ for the visit to SC. If it’s your case, maybe it’s better to buy Toolbox subscription and do it yourself. Just a thought)

There's no way they're charging me if it's just to clear some codes they didn't clear before. This is a software issue on their end. I shouldn't be penalized for this.

 

[tstolze]

I think I'm in the same boat. Since the 2022.36.20 update I've had the same errors. I had the rear drive unit replaced in August, which I believe would have included the inverter. I miss how my car was. My SC appointment is Dec 21...... Really sucks using brakes like a troglodyte. I was really concerned too since my basic warranty just ended... And this car's parts are expensive... I've been searching for days, and I'm glad I finally found this thread, so thank you.

If it makes you feel better, give this new setting a toggle on, makes it feel like regen is working, but the car applies the brakes.

To enable, tap Controls > Pedals & Steering > Apply Brakes When Regenerative Braking Is Limited.

 

[yrethguad]

If it makes you feel better, give this new setting a toggle on, makes it feel like regen is working, but the car applies the brakes.

To enable, tap Controls > Pedals & Steering > Apply Brakes When Regenerative Braking Is Limited.

Yeah I had that on already. It took me a few drives before I realized I didn't have regen. The regen line wasn't green anymore was my first hint. Great feature.

 

[yrethguad]

Does anyone know if a factory reset would clear the code?

 

[tstolze]

Does anyone know if a factory reset would clear the code?

Not sure, this was a quick process at the Service Center for me, with the details that these codes were set when I had a drive inverter go bad in early October and it was replaced. The notes on clearing these codes today were they were not able to be cleared on earlier software when the inverter was replaced and became customer facing with the newer software. All done under warranty.

 

[Atrain56]

I live 3 hours from the nearest service center and have the same two error codes popping up the morning after I updated. I've owned the car 1month so I'm not sure if they've had previous repair that never cleared the codes. Should I reboot and clear the codes myself and try driving like that? Service center wants to check the High Voltage Circuit Integrity for $410 as the fix, plus the 900$ for me to tow it there

 

[floatplane]

I live 3 hours from the nearest service center and have the same two error codes popping up the morning after I updated. I've owned the car 1month so I'm not sure if they've had previous repair that never cleared the codes. Should I reboot and clear the codes myself and try driving like that? Service center wants to check the High Voltage Circuit Integrity for $410 as the fix, plus the 900$ for me to tow it there

You don’t need a tow (unless you’re not prepared to drive there and back). It should drive fine at normal highway speeds, 70mph was fine for me. However they might need to keep it overnight, they actually had mine for 3 days due to “waiting for parts”, so consider your options for that possible delay. The loaner fleet was “grounded” due to a bout of wintery weather here, so I was stuck with the free Uber rides.

I would expect any warranty would cover this work, it is powertrain after all, did you not get that offered when you bought it? My 4-year warranty ran out 3 weeks ago (doh!), so I’m paying an estimated $420 for labor (but no parts charges??). I haven’t received my final bill yet, as it was finished late Friday and I picked it up on the weekend.

 

[Atrain56]

You don’t need a tow (unless you’re not prepared to drive there and back). It should drive fine at normal highway speeds, 70mph was fine for me. However they might need to keep it overnight, they actually had mine for 3 days due to “waiting for parts”, so consider your options for that possible delay. The loaner fleet was “grounded” due to a bout of wintery weather here, so I was stuck with the free Uber rides.

I would expect any warranty would cover this work, it is powertrain after all, did you not get that offered when you bought it? My 4-year warranty ran out 3 weeks ago (doh!), so I’m paying an estimated $420 for labor (but no parts charges??). I haven’t received my final bill yet, as it was finished late Friday and I picked it up on the weekend.

Yes that's the exact quote they gave me! Others have mentioned that if they drove for a few days this error went away, what repairs/software corrections did they end up doing for you? I appreciate your feedback!

 

[yrethguad]

Yes that's the exact quote they gave me! Others have mentioned that if they drove for a few days this error went away, what repairs/software corrections did they end up doing for you? I appreciate your feedback!

Where else have you heard stories about this? I'm just asking because I would like more information on what people have done. I'm going on about 2 weeks and mine hasn't cleared. The car is super depressing. I'm wondering if anyone in my area has access to Tesla toolbox and I can try clearing the codes. Not sure how to find that out yet. My rear drive unit was replaced under warranty back in August, and now I'm out of warranty by mileage. I feel like they're going to charge me for clearing a code that shouldn't be there for something that was fixed up under warranty. So far they haven't given me an estimate. Appointment is Dec 21. They said I couldn't come by just to clear it.