I've just mended a Zanussi Aquacycle 1200 with a similar symptom. It was filling whenever any programme was running, even when in an empty cycle. It stopped filling when no programme was running, and when switched off at the mains.
This was due to a short on the circuit board, where dampness had caused tracking, resulting in a burnt section. This shorted the surface mount transistor and activated the inlet valve all the time. There was also a smell of burning when it ran.
It was cured by taking out the board, cleaning it, and isolating the burnt part of the board by cutting a track on the back (you'll have to work out which part is not doing anything!).
Then the board was sprayed with PCB conformal coating to prevent condensation problems again.
The area that was charred was just inside the ventiallation holes in the plastic cover that houses the board, which is why it is vulnerable to dampness. So you can look in the holes to check for charring, but you may need a torch and a mirror.
Richard G, September 2005
