Genuine BMW part 61 13 6 901 665: Cover with frame OBD socket. The number stamped on the part is 61136901665; BMW's catalog files it under the short number 6901665. You will find it on our Electrical shelf, under Plug connection, terminal. It supersedes the older number 0302581, so a part carrying that number is the same part.
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 3 diagrams, among them Diagnosis plug (61_1461) and Diagnosis plug (61_1703). It weighs about 30 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.