Closing Assist/Door Lock Issues Due to Pneumatic System Problems on Mercedes-Benz S420

Problem Description and Possible Solution

Problems with the pneumatic system can cause closing assist and door lock issues.

Problem Data
RepairPal Verified
Average mileage: 137,040 (44,000–250,000)
6 model years affected: 1994, 1995, 1996, 1997, more1998, 1999
40 people reported this problem
Viewing 1 - 20 of 20 comments
When I hit the Key fob I get the indicator lights like it is unlocking or locking but nothing locks or unlocks. The trunk lid lever does not push out as normal. I have to manually lock the doors and the trunk. The lock switch on the dash does not operate either. What might be the issue. I replaced almost all of the fuses in the trunk also.
Had the same problem occur about a month after I bought the car brand new. Called MB Roadside Assistance; they did something to override the security system. Car brought to dealer. Problem due to a leaking hose in the driver seat lumbar support which is connected to the same pneumatic system. Wow; the lumbar seat control caused the security system to prevent using the car on a dark, lonely parking lot after work late one evening! "The best engineered cars in the world"???
not able to lock my car with my key remote and my trunk wont shut like it should and handle wont come out anymore how do i reset it
The trunk as well as the driver's and passenger side doors don't shut properly i.e. Closures by suction or vacuum, which is how its supposed to shut. You can forcefully shut the front doors but you can't shut the trunk without the vacuum.
my doors were not closing, I had to slam them shut. I disconnected the battery and allow the computer to reset. the doors works just fine now.
Have had some issues with vac close assist especially on the trunk. The pop out trunk handle will not pop out. Now all the doors except the drivers door are locked & will not unlock. The trunk handle will not pop out. The trunk button & the door lock button on the dash are not working. The auto locking feature when you drive over 10 miles an hour is now not working on the drivers door
Heard a snap when closing passenger door. Now door closure assist does not work on this one door. All other doors work fine. This one must be slammed to close tight.
Year is 2001 but would not let me input it above!!