Model 3 - BMS_a174 - Unable to charge, Disconnect and retry error

[schrodarkian]

Recently got a BMS_a174 "Unable to charge, Disconnect and retry" error on a 2018 AWD M3 while supercharging. I was pretty low, around 8%, charged up to 27% or so. Saw new software update notes, was fiddling with the new "Search" section at the top. Saw the new text size option, and when I changed it I was told it would reboot. Hit ok, and the car rebooted (while supercharging).

Once the screen came back up, charging had stopped. I tried to start it up again to no effect. Unplugged and replugged to no effect. Rebooted, hard rebooted, tried different stalls, etc. Nothing worked. Fortunately I had enough to get home, and for some reason it charged fine on my home L2 charger.

Sadly, road trip planned for this coming weekend looks scotched as I'd have to rely on superchargers. Anyone experience this a174 error? Any idea what it might be going on here? Never had issues with charging in 4.5 years of ownership.

No need to comment "shouldn't have rebooted during a supercharge"... I get that. Shouldn't let you do it, but I should have cancelled.

This on version 2023.12.5 on a 2018 Model 3.

 

[schrodarkian]

Crickets out here. No one has experienced error BMS_a174?

 

[jccrew1982]

Yes, I currently have the same issue with my 2018 Model 3 Performance. My bms_a174 fault first popped up about 1 month ago while charging at a supercharger. I had been supercharging intermittently for the past year on a as needed basis. I plugged into the charger as usual, and after about 3 min of supercharging the charging stopped and the display screen showed this bms_a174 fault asking me to try and reconnect. My 240v 48amp wall charger in my garage still works but I cannot supercharge.

So, being the curious guy that I am looked at the back of the charge port inside the trunk by carefully pulling back on the carpet in the rear drivers side corner of the trunk. I noticed that the mounted semi-transparent case (charge port ecu), has an internal flashing red light. Not sure if this is normal but my guess is this is the issue for me.

Maybe you could check your charge port ecu and see if the same flashing red light is occurring on yours? If so, I then I would argue this is our issue. Anyways, I'll keep you posted.

 

[drdumont]

Yes, I currently have the same issue with my 2018 Model 3 Performance. My bms_a174 fault first popped up about 1 month ago while charging at a supercharger. I had been supercharging intermittently for the past year on a as needed basis. I plugged into the charger as usual, and after about 3 min of supercharging the charging stopped and the display screen showed this bms_a174 fault asking me to try and reconnect. My 240v 48amp wall charger in my garage still works but I cannot supercharge.

So, being the curious guy that I am looked at the back of the charge port inside the trunk by carefully pulling back on the carpet in the rear drivers side corner of the trunk. I noticed that the mounted semi-transparent case (charge port ecu), has an internal flashing red light. Not sure if this is normal but my guess is this is the issue for me.

Maybe you could check your charge port ecu and see if the same flashing red light is occurring on yours? If so, I then I would argue this is our issue. Anyways, I'll keep you posted.

I would get on the app forthwith (if not fifthwith) and report the error. I can't find a direct report from Tesla, but the scuttlebutt is that there is an HV battery issue. Anecdotal evidence says the HV battery MAY need replacement. Don't delay.

 

[jccrew1982]

davewill, thank you for the comment I am going to schedule right after I finish this note. Thanks again.

 

[schrodarkian]

Perhaps this may helpful for anyone who encounters this. From Tesla service notes: "Replaced Fast Charge HV Battery Power Switch". Cost me $785. Ouch.

Fixed the issue, though. Back to supercharging.

 

[jjrandorin]

Perhaps this may helpful for anyone who encounters this. From Tesla service notes: "Replaced Fast Charge HV Battery Power Switch". Cost me $785. Ouch.

Fixed the issue, though. Back to supercharging.

(moderator note)

Its always helpful when someone circles back around and posts the solution for whatever it was they were experiencing, so thank you very much for doing that.

 

[schrodarkian]

Maybe you could check your charge port ecu and see if the same flashing red light is occurring on yours? If so, I then I would argue this is our issue. Anyways, I'll keep you posted.

I wish I had investigated as thoroughly as you!

I do think it's odd. The issue only emerged when I rebooted the car during supercharging, between 2 software updates. The latest update had no release notes, so it was a quick fix. Current version 2023.12.9, so it happened on the prior release.

Given how it happened (reboot during supercharging) I wonder if that somehow set the switch in a bad state, and it wasn't even necessarily a physical issue? Also, they said my 12v battery needed replacement as well, so maybe that was a factor?

I'll confess, I feel it's suspicious given the way it presented, but honestly I'm no electrical engineer by any means so I'm kinda stuck taking their word for it. The good ol' days of poking around in the engine yourself are over (at least for me).

Anyway, more info: part was: ASSEMBLY- FAST CHARGE CONTACTOR- HIGH VOLTAGE BATTERY(1621365-00- B), only $70, so most of it was apparently getting to the part which the service guy said was a bit of work.

 

[drdumont]

<snip>

Given how it happened (reboot during supercharging) I wonder if that somehow set the switch in a bad state, and it wasn't even necessarily a physical issue? Also, they said my 12v battery needed replacement as well, so maybe that was a factor?

<snip>

There are several possibilities.
1) It was its time for the part to die - unlikely but possible.
2) 12V batt failing - maybe, but likely you would have been notified before.
3) Electronic (solid state) relays can get stupid, and wake up in an "anomalous" state. We used a ton of them around the TV station,
and from time to time, they would go Tango Uniform out of the blue.
$785 is an Owie!, but it is hands down better than a battery replacement. I don't remember where the part is located, but it isn't unusual for
labor to replace to wayyy outcost the part. I remember the HVAC mixing door failed on our Town Car, The Money Sewer, which my wife
steadfastly refused to ditch. About a $35 part, but > $800 to remove and replace the dash. Finally some kind soul hit it in a parking lot
and totaled it, saving me a can of gas and a match. Bless you forever, sir.

In any case, glad you and your treasure are reunited.

 

[dcterp]

I know this post is a couple of weeks old. My experience so far...which is a bit of a cautionary tale for anyone who gets this fixed.

We have a Sept 2019 M3 (warranty expires in ~3 months). Towards end of last year we were getting a lot of bms a_174 and bms_a063 errors when charging at home on a L2. In November they replaced the Charge Port ECU under warranty.

That fixed the issue until the past month when it started back again. I have noticed that it doesn't fail out as quickly if charging at 30A, but still fails out. Tesla is again proposing to replace the Charge Port ECU plus the mobile connector and the charging door.

It seems strange that the Charge Port ECU would fail again within 6-7 months. I'm wondering if there is something else (more expensive) they are avoiding. I'll ask about the ASSEMBLY- FAST CHARGE CONTACTOR- HIGH VOLTAGE BATTERY and other stuff mentioned on this forum!

 

[dcterp]

I would get on the app forthwith (if not fifthwith) and report the error. I can't find a direct report from Tesla, but the scuttlebutt is that there is an HV battery issue. Anecdotal evidence says the HV battery MAY need replacement. Don't delay.

Do you have any more info on this? Links to other threads?

Worried that they are avoiding the root cause of the BMS issue that I'm having....

 

[davewill]

Document everything thoroughly so if the error returns again in a short time, you can make the case that it's the same problem you reported under warranty and should be covered if it happens again later.

 

[Konicom04]

My recent Chicago - Tampa - Clearwater - KeyWest - Chicago 3600 mile trip,

Car: 2023 MYP with under 4 K miles ( after this trip )
On the way back, got the BMS_a174 error on our second to last charging stop at about 200 miles away from home.
100F outside, with 20% charge left.

Called Tesla, they did the OTA check and the only advise was to go to an L2 charger as it is independed from DC charging,
10 hours later, we finally arrived home.,

Service scheduled for Monday 7/17. Hope they can fix that quick - I have another short round-trip planned for that week

 

[Konicom04]

One thing that just popped in my head:
I did ( out of pure curiosity ) use a 350kW EA charger in key west.
Only loaded 20% or so at modest 150 kW rate.
Wonder if that contributed

 

[akeetsEV]

This just happened to me on my model Y on a charger I've previously used with no problems. The only correlation I'm seeing is that it happened shortly after I turned on the AC to cool the cabin. Any ideas on what might've caused that?

 

[Konicom04]

This just happened to me on my model Y on a charger I've previously used with no problems. The only correlation I'm seeing is that it happened shortly after I turned on the AC to cool the cabin. Any ideas on what might've caused that?

Service center replaced the "FC Contactor - High voltage".
That was just performed this week ( Tuesday) after waiting for parts since july 6th.
Same day service, but did get a loaner for the day

 

[akeetsEV]

Service center replaced the "FC Contactor - High voltage".
That was just performed this week ( Tuesday) after waiting for parts since july 6th.
Same day service, but did get a loaner for the day

Thanks. I'll continue to keep an eye on it for now. It's charging with no problem at the moment on another charge point level 2

 

[Konicom04]

Thanks. I'll continue to keep an eye on it for now. It's charging with no problem at the moment on another charge point level 2

My issue was only related to supercharging - Level 2 charging worked fine
Apparently two separate systems ( L2 is AC, supercharging is DC)

 

[arao99]

Recently got a BMS_a174 "Unable to charge, Disconnect and retry" error on a 2018 AWD M3 while supercharging. I was pretty low, around 8%, charged up to 27% or so. Saw new software update notes, was fiddling with the new "Search" section at the top. Saw the new text size option, and when I changed it I was told it would reboot. Hit ok, and the car rebooted (while supercharging).

Once the screen came back up, charging had stopped. I tried to start it up again to no effect. Unplugged and replugged to no effect. Rebooted, hard rebooted, tried different stalls, etc. Nothing worked. Fortunately I had enough to get home, and for some reason it charged fine on my home L2 charger.

Sadly, road trip planned for this coming weekend looks scotched as I'd have to rely on superchargers. Anyone experience this a174 error? Any idea what it might be going on here? Never had issues with charging in 4.5 years of ownership.

No need to comment "shouldn't have rebooted during a supercharge"... I get that. Shouldn't let you do it, but I should have cancelled.

This on version 2023.12.5 on a 2018 Model 3.

I Recently got a BMS_a174 "Unable to charge, when charging on my zappi charger at home The charger charged for about 40 mins at 7.5kw then said charge complete. The Model 3 2022 charging equipment not ready , BMS_a174 unable to charge disconnect and retry. I unplugged my charger cable ,reinstalled and the car began charging. I have put in a service request and am waiting for a reply. I contacted my charger manufacturer who said send them the charger and they will test it.

 

[arao99]

I have had a reply from Tesla service telling me to only use the Tesla app for schedule charging. as third party app. can interfere with schedule charging.