Hi, I'm writing from Italy, in the italian Citroen Club Forum we discussed so much about this "loud bang" you are talking about, some of us spending weeks of diagnostics from various citroen's dialers, the response was even the same: no problems, no faults, probably a genetic issue of the hydractive3+ system... Below the entire discussion ;-) Saluti from Sicily! http://www.citroen-club.it/forum/viewtopic.php?f=81&t=1476