Check HV battery

[cDc1979]

Hey all. newcomer to the forums here.

Can I pick the brains of those of you who have had and/or dealt with Check HV Battery warnings popping up on the dash from time to time?

I believe this is fairly well known to happen for 2022 ish pre facelift cars looking back at a few posts on this forum.

I have recently acquired a delivery mileage 2022 MG5 from a non-mg dealer which has popped this message once. Whilst I was waiting for the new car I previously I put 500 miles on an almost exact same year and model MG5 (also from the non MG dealer) and saw the message popup and disappear almost immediately maybe 10 times in those 500 miles. They sent that car to an MG main dealer to be checked.

I had info back today that the MG dealer couldn't find any active fault codes on that car. They checked for any recalls/updates on the car and none were available. They said it might be a 12v battery issue as the car probably sat for a while - but I never noticed any battery voltage issues in the time I drove it. So basically - the dealer didn't do anything. So this sort of surprised me. So I was wondering if there is a specific update that I would need to ask the dealer for?

Can anyone point me to the correct course of action that fixed the error or recommend a dealer that I can call who has fixed this to get some further info?

Thanks very much all!

 

[Alb]

It's possible it could be a 12V battery issue although the voltage needs to be as low as 6V for 1 Second to trigger a DTC (P1E96 in this case). Setting this DTC triggers the HV Battery warning lamp which is a bit confusing, but I think it's indicating that the BMS is unable to exercise proper control with low 12V battery voltage. The DTC is cleared as soon as 12V battery voltage comes back into normal range but there will still be a historical record of the event. That history is cleared after 40 Wake-up/Standby cycles.

 

[cDc1979]

Thanks will keep an eye on that, just weird that both identical cars have exhibited the same issue and they are both 12/2022 produced cars. Doesn't seem to cause any issues, I have continued driving with no apparent issues (haven't seen any limp mode type failures)

 

[Gomev]

Just make sure you are not being too quick on the start up process, wait until 'ready' displayed before trying to select drive and keep foot on the brake throughout.

 

[PeterHR2]

Just make sure you are not being too quick on the start up process, wait until 'ready' displayed before trying to select drive and keep foot on the brake throughout.

@Gomev is quite right. You can generate all manner of 'funny' issues by too quick a start up. Only rarely does it seem to be the same reported error though. Front camera not working, collision avoidance not working, ... Must make a list. Doesn't bode well for the quick getaway when you are being pursued by the angry mob in ICEs!

Question is, is this just an MG (Win98 computer!) thing or does it affect other makes? Second thoughts, don't answer that as I wouldn't wish to derail the OP discussion.

 

[dragon2611]

Take it into an MG dealer and ask that they contact MG about it, it required a software update to be made available by MG HQ to fix.

I would get it looked at because if it does cause limp mode it's a rather unpleasant experience because the power is severely limited to the point where the car can barely move.

 

[cDc1979]

Thanks I will do just surprised they didn't do that or find anything on the other car, so any info I can find out to nudge them in the right direction is much appreciated - thanks.

 

[dragon2611]

I think it’s a rather specific software release that MG hq has to make available to that car rather than a general release. I’ve heard MGs software release process is a bit special shall we say and there’s multiple software versions floating about.

Ive had i think 2-3cases of check HV battery messages since the software fix and they were all caused by charging issues, 2 were problems during CCS handshake with rapid chargers and one was from a faulty AC charging post that one side of it wouldnt output power. (It had 2x 7kW connectors)

Pulling the 12V battery lead off rebooted the car's ecus and got it going again.