Thank you MM. The machine's outlet hose is fitted correctly as per manufacturer's instructions and isn't back syphoning. The machine is actually opening the solenoid and filling with water from the mains (into the dispenser tray). Then it drains out and switches off! I have already checked the filter and removed a pound coin and a 1p piece but the subsequent wash still ended with a new fill of water after the final spin.
CK - I stopped adding hot water to the machine last week - as soon as it started playing up - but none of the washes since then show any sign of the temp sensor resetting itself. You said it screws them up - is that a permanent thing or is it just stuck?
J. Whyte
June 2011