Leaks in the pneumatic system will cause problems with the dynamic seats and the trunk and/or door closing assist.
Car Problem Reports
Mercedes-Benz SL500 Pneumatic System Leaks May Cause Problems With Seats, Trunk, and Doors
Mercedes-Benz SL500 Problem
Average Mileage: 35,966 mi (31,900 mi - 44,000 mi)
Had to "slam" trunk. Dealer repair (at my expense) of pneumatic sensor.
Visitor, 2003 Mercedes-Benz SL500, 44,000 mi
problems with pse pump..will be replaced for second time