Miele Novotronic W833

Hi gents

The above machine will operate perfectly on drain and spin. On any wash or rinse progs, on starting it flashes either the wash or rinse light respectively for a tenth of a second then illuminates the anti-crease/finish light, at the same time lighting the red PC error light. On a few occasions, it has begun to fill then a rapid chattering noise appears from somewhere behind the front panel and the above error sequence occurs.

My first thought is pressure switch but would like a bit of reassurance!

The machine is at the end of the tightest kitchen virtually boxed in with pipes so not gone any further than checking pump/filter and float switch as yet.

Thanks for your help!