Zkw reflectors on hid headlight assembly degrade, greatly reducing the headlight efficiency at night. The plastic of which the reflector bowls are made degrades from headlight heat, and the reflective coating burns.

- Cambridge, MA, USA

In 2002-2005 BMW 330I sedans with the xenon headlight feature, BMW opted to use zkw brand headlight assemblies instead of al/Bosch brand assemblies. The zkw brand assemblies have plastic projector reflector bowls whereas the al/Bosch assembies have metal projector reflector bowls. As a result of constant heat and concentration of the xenon bulb on the plastic projector bowl, the reflective surface begins to deteriorate. Soon enough (after a few years of use) the bowls receive brown/blackish burn marks from the concentration of light. The burn marks no longer reflect the xenon light and cause the output from the xenon zkw headlight assembly to be fainter than original state. Numerous individuals on the BMW car forums have experienced similar problems and have made note that this is the cause of their failure. Note: Some 2002-2005 330I sedans did come with al/Bosch brand headlight assemblies.

- San Francisco, CA, USA

2005 BMW 320I. Tail light indicator warning came on. Turns out the wire was melted around the metal where the wire plugs into tail light!! very expensive to fix!

- Truro, 00, USA