Airmatic Rear Dropping in Sport
Thread Starter
MBWorld Fanatic!
Joined: Apr 2016
Posts: 4,764
Likes: 566
From: Milwaukee, WI
2010 C300 4MATIC........ 2011 C63 AMG.............. 2015 CLS400 4MATIC.....
Airmatic Rear Dropping in Sport
Hi all,
I'm pending to do spray leak soap/water test and xentry testing/code check. Overnight, after about 2 nights, my rear will fully drop. This only happens when I leave suspension in sport, not comfort mode.
I recently did some work where it was on jack stands and bottomed out the rear (no damage, just deflated and sitting in air).
However, both sides lower the same amount, even with the battery unplugged. This means if there was a leak even on both sides, they wouldn't fall at the same rate.
Because it only falls in sport, and NOT comfort, doesn't that mean that the valve block would also not be a problem? Although I have heard about something regarding separate chambers in a different thread.
Any ideas?
I'm pending to do spray leak soap/water test and xentry testing/code check. Overnight, after about 2 nights, my rear will fully drop. This only happens when I leave suspension in sport, not comfort mode.
I recently did some work where it was on jack stands and bottomed out the rear (no damage, just deflated and sitting in air).
However, both sides lower the same amount, even with the battery unplugged. This means if there was a leak even on both sides, they wouldn't fall at the same rate.
Because it only falls in sport, and NOT comfort, doesn't that mean that the valve block would also not be a problem? Although I have heard about something regarding separate chambers in a different thread.
Any ideas?
Junior Member
Joined: Oct 2025
Posts: 28
Likes: 11
From: North DFW metroplex
CLS 550 4Matic 2012
If you have access to xentry, I'd reccomened after the scan to follow the recalibration process for the air suspension. It's been a year since i've had to do it, but it was something to do with going forward and reverse some amount with the door open (my friend's father found some obscure instruction somewhere, I think). I don't remember if xentry initiates it (it wasn't plugged in when we drove it of course) or if it's something you can do on your own without needing the computer. Mine bottoms out whenever it's on a jack and I have to turn the car on to make it raise back up, yours could think the the car is still on jacks for some reason. That process will rule out it being an airmatic control issue and then leave you with the physical problems to diagnose. First place on the car I would check is the valve block/compressor, both are accessable without raising the car under the rear on the cls w218. The good news is either are fairly cheap and easy to replace if they are the issue.
Thread Starter
MBWorld Fanatic!
Joined: Apr 2016
Posts: 4,764
Likes: 566
From: Milwaukee, WI
2010 C300 4MATIC........ 2011 C63 AMG.............. 2015 CLS400 4MATIC.....
I left the car with the battery unplugged, and it still fell - therefore I don't think it could be a software issue...
Junior Member
Joined: Oct 2025
Posts: 28
Likes: 11
From: North DFW metroplex
CLS 550 4Matic 2012
True, though I'd say it's still worth a shot to possibly avoid buying anything. We took the jack out from the front of mine too fast one time and the front got stuck maxed out up and it persisted through battery removal until being coded out/reset. Could also be a ride height sensor that got knocked out of line or is going bad, I recall something similar happened to my buddies 08 e63 and new sensors solved his issue.
I'd say do the soapy water test and reset heights if you can, even just manipulating the heights in xentry (or any 2 way obd for this) can tell you something about the issue based on how fast or slow it raises or lowers.
I'd say do the soapy water test and reset heights if you can, even just manipulating the heights in xentry (or any 2 way obd for this) can tell you something about the issue based on how fast or slow it raises or lowers.
