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

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

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Average mileage: 136,161 (44,000–250,000)
6 model years affected: 1994, 1995, 1996, 1997, more1998, 1999
36 people reported this problem
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problem details
My central locking system for the doors won't work and my trunk will not close.
1999 Mercedes-Benz S420 200,000 mi,
trunk lid does not get pulled down all the way. The passenger door does not lock with all the others.
problem with closing/assist on doors.
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"???
1997 Mercedes-Benz S420 250,000 mi,
closing assist doesn't work, But locks and trunk does. How do I find leaking hose?
Power door locks stopped working
Power locks and trunk door open do not work
1995 Mercedes-Benz S420 147,000 mi,
Same problem, hear a sound from passenger side, but remote won't work for car locks and trunk.
1994 Mercedes-Benz S420 206,000 mi,
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.
1998 Mercedes-Benz S420 50,000 mi,
The rear doors do not use the neumatic final boost to close tight. The have to be slammed.
1997 Mercedes-Benz S420 100,000 mi,
Closing assist/door lock not working
key will not lock or unlock door,s automatic.
1995 Mercedes-Benz S420 165,000 mi,
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.
1996 Mercedes-Benz S420 160,000 mi,
havent remeid problem yet
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
i have the same problem
1999 Mercedes-Benz S420 88,000 mi,
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.
1997 Mercedes-Benz S420 150,000 mi,
Mercedes-Benz S420 : Closing Assist/Door Lock Issues Due to Pneumatic System Problems
1997 Mercedes-Benz S420 54,000 mi,
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!!