Many thanks due again guys - our ADP5966 dishwasher developed this fault today and I found the answer here on the forum! We have an extended warranty that runs until October and I thought we might have had to call someone, but the flooded base has been relieved and we are back in business.
I don't know whether this was caused by a leaking hose or a backflow from the waste, so I will monitor the situation and if it happens again, I will investigate further.
Thanks very much once again. Nice to find a simple solution to a problem for a change!