diplomat aba9242 pump always running and cant reset?

My diplomat aba9242 has failed in the last week.I originaly think it has been a frozen pipe.Now that I am sure the pipes are not frozen I have a prblem with when I switch it on at the mains it seems like the pump wants to keep running when the start switch is not on.When I try to put it into a cycle it bleeps and comes up with an error E4.How do you reset this?