2004 BMW 330 brake light sensor

This is a common problem. First thing to check is if there are any brass based bulbs, BMW cars do not tolerate them, use only the 21w silver base bulbs that come stock with the car. Second thing to check is to look for corrosion in the electrical connector at the tail lamp assemblies, in particular the brown wire which is the ground. There may also be heat damage to the plastic plug, a visual inspection will uncover this and if not too extreme, can be repaired without too much trouble. Let me know what you find, I will be standing by ♥