MG5 PFL SR out of action for 5 weeks

[Caramaddy]

A colleague’s BMW 3 series hybrid has been in the garage for 6 weeks. Battery problem - they don’t know what’s wrong or how to fix. He does have a 5 series courtesy car but payroll now want to increase his company car tax!

So not just the Chinese that have problems.

One of the directors i4 had complete electrical failure also.

Not a big survey but 2 out of 5 BMW company cars have had electrical issues.

My cousin has a Mercedes EQ something as a company car. He had to have the drive motor replaced at 100,000 miles - his colleague had the same issue. Fortunately under warranty but otherwise £6000.
VW have also had issues with software. I would go with Toyota for reliability but their range of models are very limited for a full EV.

No idea what I would change to. Interesting to see how the MGS5 fairs but customer service for MG is not good if things go wrong!

 

[Singman]

Sorry to hear about the issue you're having, I know MG aren't the quickest or the most prepared when it comes to repairs. How many miles has yours done?
I racked up 41k in my previous MG5 over 3 years and the only issue it had was the heater stopped working which took 6 months throughout winter of back and forth with the dealer to fix (faulty resistor). Then the radio screen stopped working just before I sent it back to the lease company and bought one of my own. Still love the car and can accept some issues with them for the price and cost of ownership but lead times for repairs are a joke at best.

I've done about 55k miles in the four years. There were no issues, all working fine, until it stopped working completely, 6 weeks ago. So fed up not having my car!

 

[Caramaddy]

I've done about 55K miles in the four years. There were no issues, all working fine, until it stopped working completely, 6 weeks ago. So fed up not having my car!

That would be me finished with MG, I am afraid. Fortunately we are happy with both our cars, so that decision can be deferred.

 

[PVperson]

Had my MG5 PFL SR from new in June 2021, performed faultlessly and a joy to drive. Until June 19th 2025..... a flurry of faults (Autohold fail, Hill Hold unavailable, System Fault) were displayed and it failed to start. Had to wait a while to have it towed to the local MG dealership in Warrington. Now over 5 weeks later it's still there - the speed sensors were replaced, and now another flurry of faults has been displayed to do with the main drive. At least they gave me a courtesy car after a few weeks. Wondering if I'll ever get my MG5 back. I suppose this is what happens when you mix cars with software, a Devil's brew. Has anyone experienced similar? It will be 6 weeks on Thursday and no nearer to my car being back off the slab!!

All those faults are caused by HV isolation, I had it twice in 3 years, put a 1kW fan heater under the motor for a couple of hours (you may need to remove the undertray) and then call your breakdown organisation/ local diagnostic equipped mechanic, to reset the safety faults (HV isolation) were you driving a way in the rain before this happened?
(can be in the motor, or the battery)

 

[Singman]

All those faults are caused by HV isolation, I had it twice in 3 years, put a 1kW fan heater under the motor for a couple of hours (you may need to remove the undertray) and then call your breakdown organisation/ local diagnostic equipped mechanic, to reset the safety faults (HV isolation) were you driving a way in the rain before this happened?
(can be in the motor, or the battery)

Hi, there was no rain that day - quite the opposite - a sunny hot day, and I drove home from a school visit about 25 miles away. Then later tried to start it, about 5:30pm, when it was still sunny and hot. I doubt there was any moisture involved. I've watched your video and it does make sense if there had been rain. Perhaps there was another cause.... however there was no fault saying HV isolation - just Autohold fail, then Hill Hold unavailable, then System Fault. Probably begging the question, but you'd expect MG or the dealers to know about HV isolation and to be able to rule it out - at least I hope so!

 

[PVperson]

Is the HV isolation fault occurs, it's likely water got into the HV circuit, it could have been days before. Did a technician with the appropriate software reset the faults?
The system fault (which is the major one) often includes HV isolation. Autohold fail, Hill Hold unavailable and a result of HV disconnect. You should find a local technician who can intelligently diagnose where the fault originates.

 

[Singman]

Is the HV isolation fault occurs, it's likely water got into the HV circuit, it could have been days before. Did a technician with the appropriate software reset the faults?
The system fault (which is the major one) often includes HV isolation. Autohold fail, Hill Hold unavailable and a result of HV disconnect. You should find a local technician who can intelligently diagnose where the fault originates.

This is great thanks - I work in software myself, and it does seem like these are secondary faults caused by some primary issue like HV isolation as you say. I've sent an email this morning explaining all this to the dealership - suggesting they check that the HV isolation hasn't been compromised. I'm sure they'll treat it as "What does he know", but then - what do they know? I haven't spoken directly to the engineers, just to a non-techy person who deals with customers, so hopefully my email will get through to them. Would be great if this MG dealer can deal with the MG fault, would have thought that was the right course, but am being cruelly taught a lesson in bad assumptions! an independent techy might be a better option.....