Ken,

During the first year or so after I got my 1998 E320 new, I would get defective bulb warnings but couldn't find any bulbs out. Eventually we tracked it down to the tail light housing. Mercedes really came up with a cheap way of designing these assemblies. The individual bulbs aren't wired, so the bulb gets its juice from the housing. I think the bulb holder contacts wouldn't always make a good connection with the tail light housing, causing the defective light message. The dealer replaced both tail light housings under warranty with a supposedly better engineered version. I haven't had any problems since, but I think as the car ages this cheap design will again cause problems.

Bob I.

1998 E320
1995 E420