Problem with intermittent power reduction

[Euan]

Hi there,
We have had our MG4 SE SR for over a year now and love it. Unfortunately we have experienced a problem since its first annual service last December (this included a software update). The car runs fine on short journeys but on longer journeys it occasionally reduces power for a few minutes, limiting the speed to less than 30mph and preventing any acceleration. It then recovers and drives normally. The dealer tested the car and initially could find no problem but eventually decided to replace a power controller. We got the car back in Jan and it ran fine until this weekend when the problem recurred. The car is now back with the dealer. Each time the problem has occurred the battery was more than 50% charged.

Has anyone experienced the same problem and found a solution? Thanks for any help you can give

 

[LadyCyberRosie]

It was a speed limit issue, but the error message was power reduction, speed limited was the error messages, but I noticed there was reduced power for about 20 mins earlier ie it wouldn't accelererate despite me putting foot flat down

 

[LadyCyberRosie]

Oh no! How long have you had the car?

Coming up to a year. Mg assist have said its a communication gateway error - I had all the software updated a week ago when they were checking for charging issues

 

[tsedge]

That's useful to know - so the car must be limiting speed because it cannot get the data it needs to know that faster is safe.

 

[richlove]

Interesting to see this is another early SE SR. After all the updates I had, I'm still leaning toward a hardware (battery?) issue.

Mine is going back, on Tuesday, for the 4th time to try to resolve this. Different dealer this time and 6 months on

 

[tsedge]

Interesting to see this is another early SE SR. After all the updates I had, I'm still leaning toward a hardware (battery?) issue.

Could be but also could be faulty early car modules from suppliers, which would be much easier to fix.

 

[LadyCyberRosie]

So slight update with my issue.

This is the analysos from the mechanic.

• Vehicle came in as it was not going over 50mph with a lack of power.
• Identified fault code U110E (Lost communication with BMs – ESSPTC)
• Information was sent over to MG technical which advised (Disconnect the 12V battery remove MSD reconnect the 12V then reprogram the BMS and the IMCU, once programmed replace the MSD)
• This was carried out which rectified the issue, vehicle was then test driven by the technician and a service driver both advised there was no lack of power and the vehicle reached legal speed limit without any issues.
• Vehicle was taken onto a bypass to reach speeds over 50mph

The car had been in a week before and had BMS, and other modules updated.
I asked why they thought the error happened - they didn't know, which means it could happen again.
I'm in the process of rejecting the car- I can't comfortably drive it again knowing this could happen again- I regularly drive on the motorway and this car is neither safe or reliable for travel on those roads.

 

[tsedge]

This is useful info, more evidence that it is loss of communication between car modules that triggers this mode.

If it was a software problem causing it or a problem with the MSD, then this could be the fix.

However, I completely understand why you want to reject.