Brake lamp housings can melt, resulting in a loss of contact for the brake light bulb holder. If this happens, the brake light will not work. Replacement of the damaged lamp housing should correct this problem.
Car Problem Reports
Mercedes-Benz E320 4MATIC Loss of Contact for Brake Light Bulb Holder if Lamp Housings Melt
Mercedes-Benz E320 4MATIC Problem
Average Mileage: 127,333 mi (102,000 mi - 160,000 mi)
Visitor, 1999 Mercedes-Benz E320 4MATIC, 120,000 mi
Intermittent rear brake failure even though bulb was checked good. On inspection noticed some melted or "burn" marks. Ended up replacing whole brake housing. Fairly inexpensive (less than $50) part on line.
Had to replace housing, can often be caused by using USA lamps instead of OEM lamp they are slightly different voltage causing housing to heat up and warp losing contact with lamp.
Rear brake light housing melted making it impossible to change the bulb to fix problem. Dealer popped in new housing at no charge.