drying phase fault code flashing on zanussi DE6744s dishwasher?

i've got an intermitant fault with my zanussi DE6744S dishwasher, when i select a cycle the dishwasher appears to be working fine for a couple of minutes, then the cycle light and drying phase light both start flashing. i've checked the fault code in the manual, it says the outlet pipe could be blocked or there is no water supply, both are fine. also checked under filters for blockages all ok. if i manually fill the dishwasher it will pump the water out, but it seems like the water is not being supplied or not being told to be supplied?? please help as its happening more frequently.