First pull codes and see what they're pointing at? Have you done that? Zero point in trying to make a repair without first having the codes. That said it seems the most common problem with 03-05 is the stock battery having leaked acid over time... which leaves a white residue around the battery box.... Beneath the box there is a bunch of suspension hoses that over time react to the acid powder and break down causing a pin hole size air leak which will drop the front end and or the entire car. But... pull the codes it may have nothing to do with that.My 04 plate HSE front suspension suddenly dropped. I took some advice change front ride height sensors . Still got HDC faults . Nothing seems to correct itself . Before I spend lots of money ...any ideas that might help . Thanks