My neighbor has BMW z3. He has same story about its lights, which fail more than you'd expect.

Also: It's a hard top convertible. The mechanicism stopped fully opening or closing. Bummer. Two repair shops gave ridiculous quotes to troubleshoot and repair.

Using a scanner (generic OBD II scanner with BMW's specific codes), we narrowed the search. The ultimate fix was just two $15 switches. Being noobs, it took us some effort to detach and reattach the hard top.

I don't mind the labor effort (costs). It is a BMW after all. But it's ridiculous that these cars can't report their failing electronic bits.