I have a Diplomat Dishwasher, which has a continuous bleep code F1? Help!?

Hi

I have a Diplomat dishwasher, approx 5 years old and been working fine until this morning. First thing that happened was during a cycle there is now a continous beep, beep until you open the door. The code F1 is displayed. If you turn the dishwasher off the code goes away, however, when you close again starts all over again. Help!