Registered especially to say as per RedPegLeg the above that part (J00227710) arrived and fixed the F15 drain issue on my Hotpoint. The flap seemed ok but the seal around had dissolved when compared to replacement.
One trick I noticed while waiting for it to arrive is if you put the dishwasher up on say bricks and have the drain hose coming out and down lower than the unit that sort of got around the F15 issue as it was draining away from the flap and sensor. 80{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the time it worked 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the time.