I’m new here. I have a 2008 mb R350. This car only have air bags on the rear, nothing upfront. As of last month I’ve been having so issue with the right side lowering overnight. I when ahead and changed the airbag on the right. Oh, before I had changed the airbag on the right I when ahead and replaced the air leveling sensor on both sides, only because it was losing air only when it was cold. I figured If it was warm outside the car was staying up overnight it couldn’t have been the bad airbag that was leaking, but I was wrong it was leaking. Ok so after replacing both leveling sensors and the right side airbag now left side is now lower than the right., ok so now I when ahead and replace also the left side airbag; after doing all that the left side was still lower than the right. I checked everything and couldn’t find what was the cause. Anyway after driving home I felt the suspension driving rough, only to find out the back of the car was flat out (both side). Ok here’s how far I’ve got with my troubleshooting: leveling valves arms are in place, checked fuses #32 and #53 in passenger compartment power on both sides, fuse # 108 under hood has no owner to it but fuse isn’t blown, relay G under hood has no signal power to activate contacts. When I jumped relay terminal the air compressor runs but the back of the car doesn’t go up at all. There’s no warning lights or check engine lights on in the dash. This thing is driving me nuts here!!! Please help!

Do you have a professional scanner you can hook up? You really need one.

You need to check the codes and then clear the codes.
You need to clear the old codes that were there after you installed in new leveling.

You can manually recalibrate the ride rear levels from the scanner.
If you dont have one, that is gonna be not possible to reset the system.

Your problem sounds like what I just went through.
Not all scanners can recalibrate. Only the ones that can communicate with the Mercedes.