Clogged catalytic converter?
Fix clean or gut?
If you don't have inspection in your state, it would probably be cheaper and easier to just get rid of it and get an O2 sensor spacer as a CEL boss. Otherwise, just go to an exhaust shop and have them change it, because I'm pretty sure it's welded in place in the E46.
Looking for a Used 3 Series in your area?
CarGurus has 2,009 nationwide 3 Series listings starting at $2,495.
Search BMW 3 Series Questions
BMW 3 Series Experts
Related Models For Sale
Used Cars For Sale