MG5 Mystery Faults

So just got an update from the garage, they are saying that changing the VCU should have solved the "Going into Limp mode" problem but the check HV battery message is still popping up and they have a case open from MG.

Apparently a software update is being developed to address the check HV battery message.

We will see when I pick the car up if that is the case or not.
 
Limp mode again this evening, sent the dealer I bought it from an email asking them to contact me urgently with a proposed resolution otherwise I’ll be rejecting the car as not fit for purpose.

I’m not driving around in something that randomly decides to lose all power as far as I’m concerned it’s dangerous
 
So…..

MG have had my car for a few days, they’ve cleared the faults but still not fixed the problem. They said they took it for a test drive and 8 miles down the road the “check HV battery” popped up again. They’ve since cleared this and sent all the notes to main MG who have said they don’t have any idea why it’s doing this and can’t fix the problem yet. However they are planning on making a new software update to stop this but haven’t yet done it.

So I’m still not getting anywhere really. Just got to see how I get on basically.

Has anyone else gotten any further?
 
Not yet, for me at this point it depends on when said software is available and if it fixes it, if it's going to be available "Soon" Then i'd be ok with being provided with an alternative hire car until they can fix it but otherwise it will have to get rejected.

If it was the check HV battery on it's own i'd be more willing to put up with it but can't have a car that throws itself into limp/turtle whenever it feels like it. (Usually seems to be when stopping/slowing down which means blocking a junction/lights.etc)
 
dragon2611 said:
Not yet, for me at this point it depends on when said software is available and if it fixes it, if it's going to be available "Soon" Then i'd be ok with being provided with an alternative hire car until they can fix it but otherwise it will have to get rejected.

If it was the check HV battery on its own i'd be more willing to put up with it but can't have a car going into limp mode seemingly randomly.
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Yes I can deal with the check HV battery but the limp mode is something I can’t deal with, it’s dangerous and happening way too often. Shame really as they are a great car but I’m starting to dislike it and avoiding long journeys which isn’t great and shouldn’t be a problem.

The whole situation is just stressful.
 
barry22 said:
Yes I can deal with the check HV battery but the limp mode is something I can’t deal with, it’s dangerous and happening way too often. Shame really as they are a great car but I’m starting to dislike it and avoiding long journeys which isn’t great and shouldn’t be a problem.

The whole situation is just stressful.
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You should be offered a replacement car for free!

Perhaps get Cleverley to have a look, they seem to fix all kinds of issues dealers can't!

Recently, they fix a similar issue on a Tesla - it was a £20 circuit board.
 
EVsince2016 said:
You should be offered a replacement car for free!

Perhaps get Cleverley to have a look, they seem to fix all kinds of issues dealers can't!

Recently, they fix a similar issue on a Tesla - it was a £20 circuit board.
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I don’t think Cleverley will be able to do much if it really is a software issue, presumably it’s not as simple as just downgrading to a previous version or I’d have expected a dealer to have tried that.

I suppose it could be a hardware issue that MG were hoping to work around or mask with a software fudge but none of us are likely going to be able to prove that one way or another.

I cancelled an mg4 preorder to get the 5 because they were in stock and had a similar range to the trophy 4 I had on order (dealer couldn’t even give any estimates beyond a generic 16 weeks from ordering so might have been next week might have been mid 2023 for all I knew) and I saved a few £ in the process.

I naively thought it being the pre facelift model and having been around for a while any major bugs would have been ironed out.

If they can fix the problem in a timely fashion and provide me with something suitable to drive in the meantime then I’m ok with keeping the car otherwise they’ll have to either refund or replace it with something of equivalent value / similar specifications
 
I can't understand how they can simultaneously say 'we don't know why it's doing that' and 'we're writing new software'

To write new software that resolves the issue requires knowledge of what's causing the issue 🙄
 
Ok not read the post in a while, but it looks like the advice from MG is consistent now. I assume everyone is getting "it's a know issue, they will release a software update, it's safe to drive with the random check HV message"

Not helpful if it's turtling.

Fortunately I have only seen turtle twice and once was after parking. Turtle mode cleared after turning off and on again, which is fine in a car park, but no good on a smart motorway.

Driving to Holland tomorrow, could be fun.
 
Lguk said:
I can't understand how they can simultaneously say 'we don't know why it's doing that' and 'we're writing new software'

To write new software that resolves the issue requires knowledge of what's causing the issue 🙄
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First time I put the car in for diagnosis, they didn't get any HV battery codes, so assuming they were reading the BMS for codes, and no codes appear, there is no real issue with the HV battery. This leads me to think the VCU is reporting false positives and is either faulty or can be fixed in software. They probably don't want to replace all of the VCUs, so they are probably hoping it's doable in software.
Like somebody suggested earlier, it could be alternatively sourced components not behaving as expected.

But also like earlier, this is all pretend engineering and I'm making a lot of assumptions and I'm probably completely wrong.
 
TBaLLS46 said:
First time I put the car in for diagnosis, they didn't get any HV battery codes, so assuming they were reading the BMS for codes, and no codes appear, there is no real issue with the HV battery. This leads me to think the VCU is reporting false positives and is either faulty or can be fixed in software. They probably don't want to replace all of the VCUs, so they are probably hoping it's doable in software.
Like somebody suggested earlier, it could be alternatively sourced components not behaving as expected.

But also like earlier, this is all pretend engineering and I'm making a lot of assumptions and I'm probably completely wrong.
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They supposedly did replace my VCU and it didn't fix the check HV battery or the turtleing.

Lguk said:
I can't understand how they can simultaneously say 'we don't know why it's doing that' and 'we're writing new software'

To write new software that resolves the issue requires knowledge of what's causing the issue 🙄
Click to expand...

I suspect it's different "Theys" in this case, the dealers don't know but it wouldn't surprise me if someone in MG's engineering department does but it's not something they want to disclose externally.
 
Lguk said:
I can't understand how they can simultaneously say 'we don't know why it's doing that' and 'we're writing new software'

To write new software that resolves the issue requires knowledge of what's causing the issue 🙄
Click to expand...
I suppose it's possible that they know the area of code which is causing it, and are rewriting the lot.
 
Just spoken to my dealership.
So I've got the courtesy car till the new year! MG have requested the technician reinstate my OLD BMS module as with the new one fitted they can't communicate with the rest of the system due to software mismatch! Once that's back in the car is sitting waiting in the dealership till the software update comes out.
So looks like acknowledgement that it is software errors, the other MG5LR '72 plate they have in is showing identical faults and seems we're all in the same age of vehicle.
 
There may be a software patch available but not generally so, the dealer who sold the car said it requires the VIN to be passed to MG China so presumably it's either vehicle specific or they're only allowing it for cars exhibiting this problem.
 
dragon2611 said:
There may be a software patch available but not generally so, the dealer who sold the car said it requires the VIN to be passed to MG China so presumably it's either vehicle specific or they're only allowing it for cars exhibiting this problem.
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head MG took my vin today and said an update will be coming shortly.

I’ve not taken to kindly to this reply saying shortly, it’s becoming a bit of a joke now. They told me today all engineers are out of the office until the new year 🙄

They’ve had my car on a few separate occasions now and Ive just got it back yesterday after they had it three days and later on that evening it went into limp/turtle mode.

Im waiting on a reply but them telling me it’s coming shortly isn’t good enough. I think I’m going to have to seek legal advice as I’ve had enough and seem to be going round in circles.
 
My wife and are going back to the dealer today to pick up her MG5. She has been having the same issues with the ‘Check HV battery’ warning popping up then going away, apart from the last time when the car went into turtle mode in the outside lane of the motorway.
She managed to get it going again after getting to the hard shoulder, she drove it straight to the dealer. They have had it for a week with ‘no fault found’.
When it went in the technician cleared the error log because they were “old faults”, she has only had the car since September.
I'm with you, I’m very unhappy about her driving around a car that at any moment could lose all power.
 
I have been in touch with BBC Watchdog re this problem , suggest you all do the same , maybe if enough of us email them we can get some reputational leverage from the BBC.
 
I just hope it really is a software bug related to new/changed parts and not a case of fudging the BMS to mask a hardware issue in a batch of cars.
 
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