Hi all,
So I recently had this same issue pop up, and my roof not opening correctly (back window panel stuck when trying to lift and continues to bounce up and down). I got Carista out and diagnosed it as an A696 hall sensor faulty problem, and for the part to be about £215 to replace (part no. 54377224679). Ouch.
I took it to my local garage for them to diagnose (and replace the rear pads with EBC Redstuff which I'm finding to be excellent!) and they confirmed it was the 'hall sensor that sits on the piston' itself as I had diagnosed, confirming the £215 problem.
While following this thread, the above mention came up of the hall sensor from the 1 series convertible being an identical part and being only £15. (Part Number 54 34 7 190 735). For the cost difference I figured this was a no-brainer and thought it to be worth a shot if it works.
I can say that the 1 series convertible hall sensor is almost identical, but not quite, as it is missing the connector from one end. Having traipsed around the internet I have found the follow parts to be required if you want it to be a complete kit.
Hall sensor: £15 Part No. 54 34 7 190 735 bought directly from BMW (just pretend you have a 1 series convertible to get to checkout).
Connector pins: £2.50 Part No. 61131393723 I bought them from ebay but I'm sure you can get them from elsewhere.
Connector block: £3? Part No. 8373575-02 I personally reused the one that came off the old part, but one can be bought from aliexpress with a pretty long delivery time, however it means you can just do a straight swap when the part arrives.
After that you just need cut the wires to the correct length, strip the cable, crimp the connector pins to the cable, put the pins into the connector block, then put the part back into the car. It's fiddly, but I found it could be done in place without having to remove anything.
Beeacon.