I recently got a 2011 E 350 4 Matic Wagon with 120K miles and loving it. One issue is has is with the rear left airmatic air bag suspension. Here are the symptoms:

This happens most times i drive:
- Start car - no sagging, seems fine.
- Drive car handles normal, nothing
- After 5 - 30 mins, depending, handling starts pulling right, braking causes steering to jerk left.
- Rear left suspension starts sagging.
- Suspension Malfunction error pops up on cluster.
- Sometimes coming to a complete stop the rear left suspension will rise up. Not always and if the malfunction message comes up, it never rises.

If I am at a stop, turn car off, turn it on, often the rear left suspension will rise up and set up to normal height. Also if I park and leave the car, theres never an issue with it rising up when I get in it again to drive.

Rear suspension is airmatic.

This is really only an issue while driving the car and it seems like it cant hold pressure? How can I diagnose the problem?
It has never sagged from sitting long periods, only sags while driving and only on one side (rear left)

I have the same year S212 and had the same symptoms with my left side air spring . Have the rear air springs ever been replaced? The life expectancy of the air springs @10 years before they start to leak from cracks in the air bladder. I replaced both of the rear air springs at the same time with Arnott air springs couple of years ago and it solved my problem. You could spray soapy water on all the air line connections as well as the valve body to see if there is an air leak from a poor connection. I'm leaning towards the air springs need to be replaced. Imo I would do both at the same time.

Sounds like you’ve got a classic airmatic leak or valve/block issue, and luckily, there are a few ways to diagnose it before throwing parts at the problem. Since your rear left only sags while driving and can sometimes reinflate at a stop or restart, it’s likely one of these:

1. Leak in the Rear Left Air Spring (Most Likely) – Even if it holds air when parked, small leaks can worsen under load while driving. You can check for leaks by spraying soapy water on the air spring and lines while the car is running. Look for bubbles forming around cracks or fittings.
   
2. Faulty Ride Height Sensor – If the sensor on the left rear is faulty, it might be giving incorrect readings to the system, causing uneven inflation. Check that it’s properly connected and not damaged.
   
3. Weak Compressor or Valve Block Issue – If the compressor or valve block isn’t maintaining pressure properly, one side might not be getting enough air. The fact that it sometimes corrects itself when restarting suggests the valve block could be sticking.
   
4. Check Air Lines for Blockages or Kinks – If air isn't flowing properly to the left rear, it could be due to a restricted airline. Inspect them visually if possible.
   

To diagnose further, you can use a scanner with suspension diagnostics (like a Star Diagnostic or a good OBD2 tool that can read Mercedes-specific suspension codes) to check for any stored error messages related to pressure or valve issues.

If the airbag has never been replaced, it’s likely at the end of its lifespan anyway, so replacing it might solve the issue entirely. But before doing that, I’d check for leaks, sensor faults, and air distribution problems first.

Hope this helps,

Crazy Mercedes-Benz Fan

Thanks for the super detailed response. I will test the bags. Here are the codes:

C1566
C1573
C1572

I recently got this car 2 months ago and the pre sale service report says the rear left air cushion and suspension line replacement were replaced.