I hope someone here had same problem like my 2009 GL450 4matic and can help me to fix problem. I'll start from beginning. A few months ago my rear air springs would be low randomly. My mechanic buddy had one of those expensive car software system and he manually inflated rear air springs. They stayed inflated for a few hours. Then randomly car would be leveled on its own. Also, randomly Malfunction message appeared. Making long story shorter, after researching forums like this one, I've purchased compressor, valve block, relay, four level sensors. I took my car to a local independent MB service which he says he's been in business for 35 years. I told him the problem and asked him to replace all parts I provided. He gave me quote and I agreed. He calls me next day and told me diagnoses showed right rear level sensor. So he changed right rear level sensor that I provided. He said car doesn't have problems nowhere else. Compressor and valve block works. When I went to pick up my car I noticed that rear was a little lower than front. He gave bunch of BS. Paid him left the parking lot and a few miles later car lower in the back again. When I called back he said just bring it back and will take a look at it. I've got upset because problem still exists. When I asked him if soap tested air springs he said no. He just went by what diagnosis told him. So I decided to tackle the problem my self. I replaced compressor, valve block carefully. Nothing improved. I purchased Arnott air springs and replaced them. I was guided by Arnott's instructional video. I rated the car then lowered it. Front stated raised and back bottomed down. Old Arnotts with I replaced last year were still good. In addition I read in one of threads that maybe Auxiliary battery should be changed, so I changed both battery and auxiliary battery; nothing changed. Now, I read about Level sensor links may cause the problem. I ordered the parts today. Hopefully, I'll change them tomorrow. I am so frustrated. Does anyone had any issues close to mine? if so, how were you able to fix the problem?

I had the same symptom after replacing one airbag in the rear - car would not inflate the airbag. Make sure your car is not fully off the jack/stands whe you are running it to inflate the bags. In my case, I had not installed the sensor bracket correctly during reassembly. I had disconnected it and the sensor was rotated out of the way to remove the bag. I had to rotate it back in the correct position. Make sure your sensors are installed in the correct positions.

Today, I replaced sensor rod links on both side. I put tires back on and lowered the jack where tires were touching the ground. I started the car, raised it. Now, it won't lower. I drove it around the block, rear end rocks as it had no air. I am frustrated.

I'm confused. You said you raised the car and now it won't lower, but the rear airbags have no air?