The dishwasher is about 30 months old,It works fine on rinse but on a wash program it may start with pump & fill but may beep and go to end with water check light on.
If it goes past the first section it will work fine & it may do 2-3 washes ok,its the later design with seperate reed switch.
Its strange that it will only show a fault on the first section of the program, never any water left in the tub,thinking about fitting a reed switch,
Thanks for the quick reply Roy.