2006 Airmatic S500 sagging on one corner.
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W221 S500
2006 Airmatic S500 sagging on one corner.
As above. OSR (Passenger Side Rear for the Continentals and Colonialists) drops fairly quickly after ignition shut off. Sometimes it will stay up, but not very often. Also getting the vehicle too low warning whilst driving, usually after a pothole or bump... It goes out almost instantly and no issues with the compressor side of things. And it doesn't sag when driving.
Have run all the pressure tests in DAS and they all check out except for the "Measure, leave for 10 hours, re measure... Less than 25mm is acceptable" test as it rarely stays up 10 minutes.
I have also checked, cleaned and lubricated the rear level sensor and it moves freely.
No fault codes except rear axle critical if the warning has popped up whilst driving.
No obvious hissing as the car drops. What are the likely failure points in the air lines?
Have run all the pressure tests in DAS and they all check out except for the "Measure, leave for 10 hours, re measure... Less than 25mm is acceptable" test as it rarely stays up 10 minutes.
I have also checked, cleaned and lubricated the rear level sensor and it moves freely.
No fault codes except rear axle critical if the warning has popped up whilst driving.
No obvious hissing as the car drops. What are the likely failure points in the air lines?
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Joined: Jun 2025
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From: USA
You've got a micro-leak in the airline or the o-ring inside the strut fitting. No hissing means it's tiny. Swap airlines at the rear valve block to see if the sag moves sides. If not, replace the strut's airline seal or the fitting itself. The pothole warning is just the sensor reacting to the drop.
Last edited by Alexie; Apr 2, 2026 at 09:32 AM.
Thread Starter
Super Member
Joined: Oct 2023
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W221 S500
You've got a micro-leak in the airline or the o-ring inside the strut fitting. No hissing means it's tiny. Swap airlines at the rear valve block to see if the sag moves sides. If not, replace the strut's airline seal or the fitting itself. The pothole warning is just the sensor reacting to the drop.
Does MB do a repair kit?
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S500
As above. OSR (Passenger Side Rear for the Continentals and Colonialists) drops fairly quickly after ignition shut off. Sometimes it will stay up, but not very often. Also getting the vehicle too low warning whilst driving, usually after a pothole or bump... It goes out almost instantly and no issues with the compressor side of things. And it doesn't sag when driving.
Have run all the pressure tests in DAS and they all check out except for the "Measure, leave for 10 hours, re measure... Less than 25mm is acceptable" test as it rarely stays up 10 minutes.
I have also checked, cleaned and lubricated the rear level sensor and it moves freely.
No fault codes except rear axle critical if the warning has popped up whilst driving.
No obvious hissing as the car drops. What are the likely failure points in the air lines?
Have run all the pressure tests in DAS and they all check out except for the "Measure, leave for 10 hours, re measure... Less than 25mm is acceptable" test as it rarely stays up 10 minutes.
I have also checked, cleaned and lubricated the rear level sensor and it moves freely.
No fault codes except rear axle critical if the warning has popped up whilst driving.
No obvious hissing as the car drops. What are the likely failure points in the air lines?
sounds like the level sensor link rod is doing its normal totally seized effort - and its about to snap clean off
when it throws silly data the car can get a muddle on and make one side go more mad than the small leak that makes it drop a bit anyway
don't forget unless you park on a perfectly level surface you can't trust if its a strut fault, a small leak, or if its Mercedes pretending to level the car up
Thread Starter
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Joined: Oct 2023
Posts: 568
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W221 S500
sounds like the level sensor link rod is doing its normal totally seized effort - and its about to snap clean off
when it throws silly data the car can get a muddle on and make one side go more mad than the small leak that makes it drop a bit anyway
don't forget unless you park on a perfectly level surface you can't trust if its a strut fault, a small leak, or if its Mercedes pretending to level the car up
when it throws silly data the car can get a muddle on and make one side go more mad than the small leak that makes it drop a bit anyway
don't forget unless you park on a perfectly level surface you can't trust if its a strut fault, a small leak, or if its Mercedes pretending to level the car up
Inclination of the surface makes no difference, it's always the same corner.
The strut end I can check easily enough, but where's the valve block located? I don't recall seeing it when I have had the front bumper off...
The level sensor rod did need a bit of freeing up, but it moves easily enough.
Last edited by AL5461; Apr 2, 2026 at 10:41 AM.
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S500
right rear sagging is in a USA TIPS doc on early cars - they ruined the plastic pipe on early builds - it specifically calls out must be new pipe front to back - never add joining bits - they must have dragged through a bad weld of such and scored along the length of the pipe till it weeps
Thread Starter
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Joined: Oct 2023
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W221 S500
right rear sagging is in a USA TIPS doc on early cars - they ruined the plastic pipe on early builds - it specifically calls out must be new pipe front to back - never add joining bits - they must have dragged through a bad weld of such and scored along the length of the pipe till it weeps
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2010 E550, 273 Engine: 2012 S550, 278 Engine
Replace them both.
