diplomat dishwasher ?

Our dishwasher is fitted into kitchen, it has recently started beeping and displaying F7 in screen when turn it on, we have it sitting out from the units at moment and it was working again until we put the left hand side back on and now it is playing up and going through the same thing again. Has anyone any ideas how we can fix it? It's Hygena Diplomat dishwasher model ADP8332