Micro switch, trunk lid key button — a genuine BMW part, number 51 13 8 185 792. The number stamped on the part is 51138185792; BMW's catalog files it under the short number 8185792. You will find it on our Interior Body shelf, under Other Body equipment parts.
It fits every E46 body style (320i, 323i and 325i, 1999–2006), with the M52, M54 or M56 engines — and the European-market versions.
BMW draws it on 5 diagrams, among them Single Components for Trunk Lid (41_1318) and Single Components for Trunk Lid (41_1367). It weighs about 5 g (under 0.1 lb).
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.
