Just joined, first post. Can't find any good european forums!
My UK based 2001 E46 has a fault / problem with the rear lights, as follows:
1. When left indicator flashes, rear right brake light also flashes.
2. When right indicator flashes, all OK.
3. When foot brake is applied, rear left indicator comes ON (not flashing).
4. With sidelights ON, rear left indicator is ON (weak, not flashing).

I've checked wiring and lights at rear, and see no obvious faults, i.e. shorts or melted components as suggested in a couple of other posts here.

Any suggestions?

Try posting this in the E46 portion of this forum. You may get more response there.

Have you had this problem since you had the car or has this become a recent occurrence?