My left driver's side works, passenger right back does not. The bottom heats but not the back.

Photos? thoughts? ideas?

:frown:

Sound like the heating element (6) or the wire leading to it has failed.

http://www.realoem.com/bmw/diagrams/z/o/228.png

I guess it would be worth checking the multi-plug under the seat and maybe cleaning the contacts, in case the problem is there.

I've stripped my backrest down to add the adjustable lumbar support and the heating elements are sandwiched between the seat cover and the foam (fairly obviously!). That means an upholsterer's 'hog ring' machine is required to open and particularly to replace the hog rings holding the cover to the foam - where all those little 'tick marks' are in the diagram on item (2). So if the element needs to be replaced, it's probably a job for an auto trimmer. Real OEM says the heating element costs US$76.

I've done a PDF write-up on how to add the lumbar support and that shows how to strip the seat back down - it might save you some money if you did that and then drove the car to an auto trimmer like that. PM me with an email address if you want a copy of that PDF, as it's too big to post here as an attachment.

Ive done loads of seats and have only ever used various pliers on the hog rings, just watch your fingers.

Aye, hog rings always bite back.

This Discovery video of Mini seat production shows the bits - hog ring doodah at 1:35:

How its made - Car seats - YouTube

or possibly in Canuckia:

How It's Made Mini-Episodes: Automotive Seats : Video : Science Channel (http://science.discovery.com/videos/how-its-made-mini-episodes-automotive-seats.html)

Fascinating video - thanks for posting it!

Apparently hog ring pliers aren't too hard to find. On that production line, it looks they're using automatic pliers of some sort - electric or pneumatic. Harbor Freight in the US carries regular manual hog ring pliers, so I'm sure you could find them easily online or at a hardware store.