One problem related to brake hoses, lines/piping, and fittings has been reported for the 2003 Mercedes Benz E Class. The most recently reported issues are listed below.
Mercedes benz E Class and sl class 2003 2004 models with electro-hydraulic brake systems are experiencing brake failures, sometimes within 1000 miles of purchase. Electrical failures can leave the vehicle with no rear brakes and limited use of the front brakes! some of the brake lines are rubber and attached with hose clamps! I have worked on cars for fifteen years and had not seen a brake failure, but have now seen three in the last three months. When these vehicles age, complete brake failures may be possible.