The electrical connector at the automatic transmission may leak fluid into the wiring harness. If not repaired, the oil will migrate through the wiring harness and damage the transmission control module. At that point, a new harness and control module may be necessary to correct this problem.
Car Problem Reports
Mercedes-Benz E500 Wire Connector on Transmission May Leak Fluid and Damage Control Module
Mercedes-Benz E500 Problem
Average Mileage: 103,824 mi (82,000 mi - 125,000 mi)
Transmission sticks in first gear. The only way to fix is to turn the engine off and restart. Very intermittent problem. When it does happen, it seems to repeat itself for a few days, until the car sits for a day or two of no driving. Then it will not have this problem for a couple of months.
Visitor, 2003 Mercedes-Benz E500
systematically replaced the control module, radiator and transmission - total cost was over $7000