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.

 

[Atrain56]

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.

This member here! Didn't end up specifying how long until codes went away though

 

[floatplane]

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!

I drove it for at least a week, and the alerts didn't go away.

The invoice finally arrived, and it is $0.00! The rear inverter was replaced and apparently was covered by "Drive Unit Limited Warranty". Thats surprising as I thought my warranty for everything but the battery pack had expired a month ago.

 

[Oversmith]

Same issue with my 2018 car. they replace the PTC heater and the wire to it. (1088218-00-I) and (1109004-10-G) I really did not think this was the problem, but one day from dealer and no issue. Cost 1.1k

 

[Rvilla1234]

Recently notice this code and another one on my 2018 model 3 LR.

Setup a service appt and was quoted over $500. I’ll let you all know how that works out after they have a chance to diagnose.

 

[Atrain56]

UPDATE: Problem fixed (for now)
Had mobile service come and clear the codes! Just as I suspected, it was a software issue. If codes pop up again I will let you all know but it looks like I didn't have to pay a dime and the problem is solved.

 

[yrethguad]

I've had a different experience. Seems to vary by service center. So I informed service about my findings, how other owners have the same error after the same update and have had the same previous work done, what other service centers have reported, etc. I asked if mobile service can just come out to clear the codes, and they said no. I asked if I could just stop by the service center and have it done, and they said no (in lieu of waiting a few more weeks for my appointment). They said these vehicles are not like other makes where you need to clear codes. They will erase automatically when there is no longer a problem. They said following what other owners say on forums is not a viable way to diagnose a vehicle, and since I'm now out of warranty the estimate is $500 in labor to diagnose. I looked back and I didn't mention finding any information on forums....

Anyways, with the help of you guys I found someone local that has the toolbox software, got the codes cleared, paid him for his time and help, and now the car is back to normal.

 

[Trish25]

2018 Model 3 here with the same problem. I have an appointment with an estimate of $480 for labor for "high voltage circuit integrity check". My bumper to bumper is expired, but I still have my drive unit and battery warranty and I would expect this to fall under that so I don't actually think Tesla will end up charging me anything. I will update after my appointment.

 

[Atrain56]

I've had a different experience. Seems to vary by service center. So I informed service about my findings, how other owners have the same error after the same update and have had the same previous work done, what other service centers have reported, etc. I asked if mobile service can just come out to clear the codes, and they said no. I asked if I could just stop by the service center and have it done, and they said no (in lieu of waiting a few more weeks for my appointment). They said these vehicles are not like other makes where you need to clear codes. They will erase automatically when there is no longer a problem. They said following what other owners say on forums is not a viable way to diagnose a vehicle, and since I'm now out of warranty the estimate is $500 in labor to diagnose. I looked back and I didn't mention finding any information on forums....

Anyways, with the help of you guys I found someone local that has the toolbox software, got the codes cleared, paid him for his time and help, and now the car is back to normal.

Service centers of all vehicles are helpful absolutely, but at the end of the day they're just trying to make money like every business. Good on you for getting them cleared and fixed without having to wait and pay them $500!

 

[Trish25]

2018 Model 3 here with the same problem. I have an appointment with an estimate of $480 for labor for "high voltage circuit integrity check". My bumper to bumper is expired, but I still have my drive unit and battery warranty and I would expect this to fall under that so I don't actually think Tesla will end up charging me anything. I will update after my appointment.

UPDATE!

Took my car in on Saturday late afternoon, was given a loaner, and Monday I got a notification that my car was ready and fixed. She is back in my garage right now (Monday evening). Total price: $0

I have a new drive unit and 12V all covered under the drive unit warranty. I would not ignore or try to dismiss these messages if I was you. Overall the entire experience was no more inconvenient than getting an oil change (my in and out was certainly quicker than one).

 

[robstrash]

Yikes, our 2018 LR M3 from July 2018 just got the BMS_a170 and BMS_a027 warning messages tonight. We were supposed to drive the car down from NJ to MD on Christmas but looks like we'll be taking the Toyota instead. The Princeton service center is full like always but we got an appointment in Eatontown NJ on 27 Dec. Hopefully they won't have to keep the car as it's a 30 minute drive. Since our main warranty ended hoping this is covered under the 8 year power train warranty but guess we'll find out next week. We've never had any service done other than air filter and charge port door so it's definitely not an error from previous repair.

 

[Sdjtd]

Yikes, our 2018 LR M3 from July 2018 just got the BMS_a170 and BMS_a027 warning messages tonight. We were supposed to drive the car down from NJ to MD on Christmas but looks like we'll be taking the Toyota instead. The Princeton service center is full like always but we got an appointment in Eatontown NJ on 27 Dec. Hopefully they won't have to keep the car as it's a 30 minute drive. Since our main warranty ended hoping this is covered under the 8 year power train warranty but guess we'll find out next week. We've never had any service done other than air filter and charge port door so it's definitely not an error from previous repair.

Same thing happened to our 2018 LR RWD (41K miles) a few weeks ago while on a road trip in Arizona. Stopped to take some pictures in Sedona, got back in the car and these two alerts appeared. Yes, Yikes! Message said car was OK to drive, albeit with limited acceleration and top speed and no regen. Also confusingly said performance might return on next drive and that the car may not start on next drive??? Well, drove OK to our next stop in Cottonwood, called Tesla service, and they advised it would be OK to try and drive 100 miles to the nearest service center in Scottsdale. Did so the next morning without any issues. They took us right in and said it would likely be a couple of days to diagnose the problem. Much to my surprise I got a notification about 40 hours later saying the car was repaired and ready to be picked up. OH Great, I thought, this means they didn't find anything. A few minutes later the repair invoice arrived in the app and lo and behold the entire rear drive unit and the original 12V battery had been replaced, all covered by the drive train warranty. So kudos to the the staff of the Scottsdale center.

Now, if I can just get Tesla to fix my 1/3 crippled PCS which I didn't discover until the 4yr warranty expired I'll be a happy camper.

 

[nospoon408]

I've gotten this errors (BMS_a027 & BMS_a170) since Dec 14th with the Software update. I've scheduled an appointment for the 20th and they moved it to Jan 2nd to give the virtual technician more time.

Really hope they could just reset the error or tell me what's wrong. Sucks driving in this condition of the car.

Previous work they did:
Feb 2021, replaced the v12 batter
August 2022, replace the Driver Unit

 

[sandrews]

Following this thread. I received the same 2 errors after the software update. The car is now in the shop for a $440 "high voltage circuit integrity check". We'll see...

 

[robstrash]

They had our car for about 26 hours and we stupidly said to please replace the 12V battery since it's 4.5 years old and knew that would have gone next. Looks like we could have gotten it done for free. Oh well, it was only $105. The invoice shows:

Correction: Inverter - Rear Drive Unit (3DU) (Remove & Replace)
Correction: Cooling System - Vacuum Refill (Add Coolant 1029320-00 if Needed)

It seems to be working fine now. Used the Uber credits since it was a 45 minute drive. Weird that the way home was $98 but the trip back was only $61. Both trips in middle of the day so not idea why it was so much higher but it was $100 per day so just glad I didn't have to pay.

They also did the Retrofit the Trunk Lid Harness.

 

[nospoon408]

Finally they replied with "high voltage circuit integrity check" $510 and no alternative transportation. Tesla service has gone down a lot.

 

[Trish25]

Finally they replied with "high voltage circuit integrity check" $510 and no alternative transportation. Tesla service has gone down a lot.

Did you actually take it in or is that just based on the texts? I was also quoted a fee, paid nothing, and was given a loaner.

 

[nospoon408]

It’s current with them and they did it give me a loaner at all. They just finished the work and want $510 but I’ll wait until tomorrow to talk to the representative

 

[nospoon408]

Update:
Went to pick up the car and spoke with the service rep. He remove the $510 charge since it was a cause of the last visit (replace driver unit)

 

[Sylveon]

I’ve recently experienced this same pair of error codes, popping up not long after a visit to the dealership for a pet replacement. Can anyone connect me with anyone in the greater atlanta area who can look at and possibly reset this code with me? (since getting an appointment for Tesla to do it is going to take a LONG time, given that it might be a simple holdover from something being re-connected improperly after my previous service)

 

[Sylveon]

I’ve recently experienced this same pair of error codes, popping up not long after a visit to the dealership for a pet replacement. Can anyone connect me with anyone in the greater atlanta area who can look at and possibly reset this code with me? (since getting an appointment for Tesla to do it is going to take a LONG time, given that it might be a simple holdover from something being re-connected improperly after my previous service)