Hello! Not sure if this is the correct part of the forum to post.
I have a 2011 S212 E220 estate, RHD.

Over the past 2 years, as with others, I have had a problem with the rear air suspension. It’s not the full 4 corner airmatic, just bags on the rear as it is an estate. Overnight the car would sink down, and when I started it the next morning it would rise up. Eventually the car just stopped rising up. Therefore it sat on the driveway for a good few weeks until one day, when I happened to turn it on, it rose up! And worked for about 2 months straight (sinking overnight, rising when used).

At the start of this year it finally stopped rising altogether, myself and mechanic came to the conclusion that the compressor wore itself out as it was constantly having to turn on to keep the car rising up. I bought aftermarket bags and compressor and got it fitted. Perfect, car was nice and high as normal, didn’t drop down at all overnight. That lasted for a week. Suddenly the same problem, dropped down fully and wouldn’t budge, still getting a ‘vehicle rising please wait’ message, but no movement.

Now I know there are ride height sensors on the left and right, just next to the bags, but my question is, is there a centre sensor? I ask this as a guy I know had the same problem and said there is an additional sensor in the middle rear of the car, underneath a heat shield. I didn’t know this, and apparently neither did mechanics. So much so, he rang the local dealership asking for the central sensor. The said ‘there isn’t a central sensor’. He then apparently read out the part number and they were then like ‘oh…. I think you’re right, there is’.

Has anyone seen or personally dealt with this supposed central sensor? Before I ask my mechanic to spend his time (and my money) searching around for it? No ramp myself at home to have a look, and I don’t trust my 2t car on Jack stands! Any other help or advice on the issue would be appreciated. Tempted to change to coils if it goes unfixed.

Thanks all, I appreciate the help. If this is in the incorrect section please let me know where it would be better posted for an answer!

 

I had similar experience with my '11 S212 about two years ago. In my situation the left air bag had micro cracks on the rubber bellows which would allow air to escape and lower the left side of the vehicle overnight. In the morning when starting the vehicle, I would get the message "vehicle rising please wait". I bought Arnott replacement air bags, installed them and it resolved my situation. You stated that your air bags and compressor were both replaced. Do you hear the air compressor cycling to inflate the bags or is it silent? If your compressor is operating normally and trying to fill the air bags then there is a leak at either the air fittings at the air bag connections, the central valve block, the air lines themselves or the possibility that the new air bags/compressor installed are defective. Try using a bottle of soapy water and spray it on all the connection fittings and watch for air bubbles at each of the fittings including the central valve block. This will indicate whether air is leaking from the system at these connection points.