E63 645ci 2004 transmission problem

[nadaall]

Hi guys,
I've had this issue with transmission for over 2 years (my car has been kept in my local garage for the last 2 years). The guy couldn't find the problem. Transmission fluid was replaced. He suggested that I need to buy the whole transmission (part number Ga6hp26z).
My question is: are the transmissions from 5, 6 and 7 series interchangeable?
One of the ebay sellers said that most of them are. However I found that this part number also comes up with for example transmission from 3 series diesel.
Your help will be greatly appreciated.
Thank you

Sent from my SM-N960F using Tapatalk

[Timm]

What is the problem with the transmission? The garage changed the fluid so they must have thought the gearbox had a chance.

[nadaall]

What is the problem with the transmission? The garage changed the fluid so they must have thought the gearbox had a chance.

It goes into the limp mode, iDrive shows "transmission fault", doesn't go higher than 3rd or 4th gear. Fluid was changed at other garage, guys at this one suggested I should buy new transmission, as they tried few things and have no clue. So far it cost me £1500+ and still no fix, so getting replacement transmission I think is my last option.....

Sent from my SM-N960F using Tapatalk

[Timm]

Have the Mechatronics seals been changed? They are usually the cause of these sort of problems: https://www.meeknet.co.uk/E64/BMW_E6...earchanges.htm

[nadaall]

Have the Mechatronics seals been changed? They are usually the cause of these sort of problems: https://www.meeknet.co.uk/E64/BMW_E6...earchanges.htm

I'm pretty sure it was. First mechanic who replaced the fluid replaced the seal as well.

Sent from my SM-N960F using Tapatalk