Like willyb I am a new member too and have the same problem. When my 2011 C5 was new and up until about 6 months ago it would lower itself when parked. When starting up again it would raise itself. Now it just stays the same height all the time. No error messages and the garage replaced sensors and says everything is ok. I can manually raise or lower it using the buttons but it doesn't do it automatically any more on parking up etc.