2011 gl550 sagging in font intermittently
 

hello, I have a 2011 550 and about a couple weeks ago it all the sudden dropped to the ground in the front. It will happen sometimes when I lock the car and I can hear hissing sound, and feel air releasing from the bottom of the front airbag. I thought it is leaking and need to be changed. However this would not happen all the time. Sometimes the car stays at its hight when I park it and it won't drop, and no air releasing from airbag, even parked overnight. It would also happen when I'm driving in a bumpy road, it would drop and I feel the car ridding real bad, and when I stop, the compressor kicks on and raise the car back up. I bought a iCarsoft MBII on amazon but no code found in Airmatic module, no warning on dashboard.

This is a very normal thing to happen with air bags - regardless of what brand car they are on. It's also been talked about to death on here in many, many threads. If you want the long story, search those threads. The short story... replace the bags or the entire assembly (easiest).

I guess what I’m trying to ask is if the bag leaks intermittently does that mean it’s the bags that’s no good? Sometimes they don’t leak whatsoever. Also when I’m checking on the scanner; the voltage keep going down on the front right leveling sensor.
https://cimg4.ibsrv.net/gimg/www.mbw...a8918201f.jpeg

That's part of the long answer - did you search for other threads and read up? But, you answered your own question in the first post... you heard/felt air leaking out the bottom. In other words, it's got a hole! I'm not familiar with the voltage readings on the sensors.

Replace the darned strut already.

Every day you wait you damage the compressor making it work twice as hard

I had the same thing happen to me. In my case my front passenger side strut would hiss occasionally and bottom out. It was not consistent and happened randomly. The leak eventually wore out the compressor and I ended up having to replace the compressor and the front passenger airbag/strut assembly. I’d recommend replacing the airbag or the entire airbag/strut assembly (just on the side that’s leaking/hissing) before the compressor gets worn out. As a side note, eventually you’ll have to replace all the airbags/struts on that car. In my case, I had already replace the other three corners over the years. You might want to consider doing both fronts if they are still OEM.