The dishwasher reported a heater fault on its front panel lights, I tested the heater and found it open circuit, I replaced the heater and it worked. A few months later the same happened, Hotpoint sent me a new part which I fitted and the dishwasher worked, for a few months, when the same happened again.
The fourth heater has now failed so there is clearly something strange going on: it is beyond me why a heater should fail in this way, the dishwasher functions normally (when the heater is OK), it washes correctly and I’ve cleaned out all the filters and checked all the pipes I can. The pump impeller seems OK and the pressure inside seems OK when it is washing.
Any advice appreciated!