What does error E1 on Kenwood KDW243A Dishwasher mean?

It happens a couple of minutes after I switch it on for a wash.

Emma Griffiths, January 2008

I have just bought a KDW243A Diashwasher and spent 2h tyryinh to get it working with it beeping at me and showing E1 - The problem is that the dishwasher is NOT receiving water - make sure the cold inlet is conected (and in my case) that the plumber has turned on the isolator (stop valve)

Lawman, February 2008