The ESP and BAS warning lights may illuminate due to a failed brake light switch. Replacement of the failed switch should correct this concern.Google+
Car Problem Reports
Mercedes-Benz SL550 Brake Light Switch Failure May Cause ESP/BAS Warning Lights
Mercedes-Benz SL550 Problem
Average Mileage: 60,100 mi (59,500 mi - 60,700 mi)
Visitor, 2009 Mercedes-Benz SL550, 60,700 mi
Intermediant ESP warning light activated. STAR diagnosis pointed to the switch. Replaced brake light switch. $220 at INDY.