Hi Folks, Just an update on this post, I fitted 00631199 Valve-outlet For heat exchanger and the fault cleared, I did check the old unit and it was open circuit. Just a word of warning when you remove the valve from the side water tank, it empty’s it’s contents into the base of the dishwasher I cannot really see a way around that. Thanks to Jem for responding, I had seen the valve reported on another website, but nice to be pointed in the right direction Regards Neil [h=1][/h]