2013 Cadillac XTS AWD. Self leveling system service soon message.

What is your question?

Compressor works. Rear rises and lowers but doesn't go as low as it used to. Right rear seems to be very stiff as if over inflated.If you roll over a cricket you feel and hear it with a thud. When the car is parked and turned off, the air is released and the rear lowers slightly. I do remember it used to lower much more, but now not so much. Is there a sensor that can clog or go bad?

What makes this problem better or worse?

.

How long has your 2013 Cadillac XTS had this problem?

few weeks