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 S430 Brake Light Switch Failure May Cause ESP/BAS Warning Lights
Mercedes-Benz S430 Problem
Average Mileage: 122,400 mi (84,000 mi - 144,200 mi)
Visitor, 2000 Mercedes-Benz S430, 84,000 mi
ESP and ABS light stayed on. Its in the shop for the 3rd time. I am suggesting that they change the brake light switch.
BAS/ESP message lights would at times come on. More and more frequently. Replaced the Brake Light Switch,resolved this problem! Thanks