Chosen Solution
I have a Miele G868 dishwasher, which is maybe 20 years old at this point, but has always and still works very well, running on average once a day completely full. We do clean out the action parts regularly, and they still are in pretty good condition. Recently the main tub has started to occasionally and very slowly fill with water when the unit isn’t running. For example, the machine is run at night before we go to bed, and in the morning there is a half inch of water in the bottom. The longer we leave it, the more water we might find. So it seems to take many hours to “fill” this way. Before we knew what to look for, it even seemed to overflow into the safety basin underneath, which I had to sponge out. (You can tell, because the pump will run but never shut off, since it can’t pump out water from there.) This only happens sometimes, not always. The door can be closed/locked or not - doesn’t seem to matter. I have verified when this happens that at the end of the cycle there is a normal amount of leftover water (basically very little or none), and I leave it for several hours and there is more water than before. The pump/drain action works fine. As soon as I turn on the machine to run, it’ll empty all the water as expected, whether it is a normal amount or more. I have also pulled out the backflow preventer, which is easily removable from the inside of the tub. I tested it by filling it from the outbound end and it seems to work fine in that no water goes through. It seems to be in proper condition with no debris or damage visible. Also, when you remove it, a few cups of water does immediately spill into the basin, indicating that the preventer is doing its job in keeping that water out normally. In addition, the spinner (impeller?) underneath it also seems undamaged and clean and will spin when manually pushed. (There is always a bit of water around it, though, so hard to say if it “spins freely”, but it would seem there isn’t a problem with it.) Thus, my conclusion is that water is being let in occasionally via the intake control valve, not the outlet system. So, my question: Is there an obvious self-fix for this? If so, what part would I replace? I have a parts diagram, but it isn’t labeled with what each part does. There is a box in-line with the intake hose, but is that the valve itself, or is there something underneath in this model that I would replace? Or is it not something I can do as a non-expert?
Update (09/28/2022) Yes! I actually took a whole bunch of notes and they ended up on this youtube video that showed exactly what I needed to do: https://youtu.be/iW3_AnJ9C5s
Does that box at least somewhat resemble this? If so, this is what needs replaced. The water valve is inside that box, according to everything I’ve been able to find about this make and model. The parts diagram should provide you with a part number to make finding a replacement easier.
