I have the exact same problem with my Xantia Estate. Did you manage to get it sorted and if yes would you mind telling me. I can raise front end to maximum and lower it to mininum but cant get it to normal height.
Martin, February 2011
sounds like front height corrector faulty but it could be the adjuster it may have snapped , the adjuster goes from the height corrector to the anti-roll bar hopes this helps
