I just purchased a 2006 DTS. The left (driver side) headlight has moisture in it. Does anyone know of a fix that does not involve purchasing a complete new unit from the dealer?

 

Some guys will drill a drain hole in an inconspicuous place in the headlight cover using a small diameter drill bit if there is a significant quantity of water in there. If it is just misty then the moisture is getting in because the seal is not perfect or there is a crack in the cover. In the case of a crack some carefully applied super glue may be enough to seal it. In the case of a bad seal some carefully applied silicone sealer may be enough to seal it. Before doing either make sure there is no moisture in the lens. A blow dryer usually clears it up.

 

Thanks. That is essentially what I did. I didn't drill a hole but I did dry it out really well, made sure the vent tubes were open, put a few grains of white rice down in the bottom where they don't show, and ran a bead of silicone around the joint where the clear plastic joins the black plastic. Also covered a few minor cracks with the silicone. So far, so good.