Indesit IDL730 Lights 1 & 3 flashing?

Our indesit IDL730 is not working. The original problem was a faulty hose, which we have now replaced. We now have both lights 1 & 3 flashing. The washer starts, prewash (1) light goes on as normal, then rinse (3) light goes on and the dishwasher just keeps churning.
This is very infuriating. We have tried opening up, looking at the pressure switch, checking the mesh, checking the hose - all seem fine. Any ideas?