Hi I have a 2014 520d manual. I have Intermittent brake loss, RAC couldn’t see anything obvious and suggested master cylinder.

the pedal randomly hits the floor when pressed and the car barely stops. Tested it this morning and it seems to be working fine.

obviously not driving it about as they could fail again. Have it booked it at an indi BMW workshop.

has anyone had this issue?

 

My obvious first question would be was brakes/fluid done recently? If not then I would think it's an abs module before the master cylinder. We're any tests done? Was vacuum checked? Was it checked for any leaks

 

I’ve owned it 3 years and not had the fluid done, had new front brakes and discs when I bought it, then I had the rear discs and pads done about 4 months ago. Plenty of pad out n the front but they have squealed for the past 2 years 😬.

RAC didn’t do any electrical diagnostic, he said it wasn’t worth it.

 

I was was referring to some ISTA testing. I wouldn't think this issue has anything to do with electrical testing. Just let us know what the Indy comes up with. I haven't heard of these issues in the F series before.