Need new Brake Sensors? http://www.amazon.com/gp/product/B007PSFNEI/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B007PSFNEI&linkCode=as2&tag=bullshitkor01-20&linkId=VMBWVIVYVVOBARPK
This is another BMW 3 Series E46 project that you can do yourself without any tools at all. sometimes but not all times the brake light could mean a cable has broken. The E46 has 2 one on the front rotor and one on the rear rotor. The cables are pretty cheap to buy and can be installed with just removing the tire and feeding the new wire after removing the old one.
this job will take you about 1/2 beer