Thanks for the reply. The light wasn't flashing.
However, I filling the machine with salt (which is something I had never really bothered with) and this cured the fault. :oops: :)
This built-in dishwasher has worked fine for several years.
However, it's wash programs now don't finish. It just keeps washing - forever. The only program that does complete is the quick rinse cycle.
I have reset the controls, but no joy. I also have noticed an irregular, quiet beeping...