I believe most dishwashers in general will keep some water in the sump area. I'm pretty sure they don't completely drain all the water.
That's true Bryan, they're using centrifugal pumps and need to leave water to keep the pump primed. They simply can't pump all the water out, it's not possible. The centrifugal pump needs a constant supply of water to work, the only way all the water would get pumped out is if the pump could move air to clear the line, which of course it can't, or if they used a gravity drain. The same idea applies to clothes washers.
I found the convection roast relay burnt, although not stuck (problem was intermittent on convection roast cycle). For comparison I checked the bake relay, which was also burnt, but not as bad. See image of convection roast relay below. Replaced relay board 817752. I'll wait a few days before claiming this is resolved because she needs to cook with it for the real test, but based on the condition of the relay I'm fairly certain it's fixed.
For comparison - bake relay and below that pizza element relay (which gets zero use):
If you have ice, as opposed to frost, on your evap then you have a sealed system problem and will need to call in a pro, the materials for that job are not available without a license and requires a high degree of skill.
The fresh food section doesn't have a defrost system on this model. If you have light frost check the evap fan (and fan switch) as well as the door seal.
The fresh food and freezer are essentially two separate systems. You probably have a sealed system problem in the FF section, that's common for this model.
Update: Top solo valve (Part number 5268871) resolved the issue. By the way, although it's called a top solo valve everywhere in the tech literature, parts department wants to call it a circulation valve.
In any case, the first image is the new top solo valve in the normal position, ie top solo option not selected. The plunger holds the ball in place allowing water to flow through to the lower spray arm (0.68K ohms through the solenoid).
This image is the old, broken TSV, showing the ball out of place, which is also where the bball would be if top solo was selected, blocking the water path to the lower spray arm, held in place by pressure out of the circ pump.. That is the correct orientation of the TSV, it looks like the ball simply falls back into place on the bottom once the water pressure has been reduced, allowing the plunger to hold it again.
TSV disassembled. The plunger is broken, that collar should be against the casing. The resistance is good though, 0.675K ohms.
No need to be a Miele specialist for this, all the relevant info is included below. You certainly know as much about this particular problem as I do. Also a good schematic skills exercise.
I was out on a Miele dishwasher this afternoon, G863 SCVI Plus. The complaint is the bottom rack is not cleaning. I found the lower spray arm not turning at all. The spray arm is not clogged, the filters are not clogged. This model has a "top solo" option which blocks the water to the lower spray arm, allowing only the upper spray arms to operate. There is a "top solo" valve (TSV) which is used to accomplish this. It is an electromagnet that releases a ball into the water path which is held against the TSV outlet by the water pressure coming out of the circ pump. I found nothing blocking or clogging the TSV. I found the ball within the valve loose. I found 120VAC to the valve, momentarily, only when the "top solo" option was selected. I found resistance through the valve circuit, Miele does not offer specs for that.
So, to be sure I was diagnosing correctly I called Miele tech support. The first tech essentially told me just replace the TSV, that it couldn't be tested. I called back after leaving the house, the second tech told me it's testable through a component test (which is true). He also said that the ball should only be free when power is applied, that without power it should be held in place by the TSV solenoid. He also said that the TSV should read infinite ohms when not powered. Only part of that made sense to me so I double checked the schematic, it looks like the TSV circuit should never be "open", but the voltage supply is switched by the electronic. So I think he was incorrect about reading infinite ohms without power applied. It does make sense that the ball should only be free when top solo is selected, but I'm not certain that power needs to be applied to release the ball or if power should be applied to hold the ball. Based on the voltage readings I think it's likely true that voltage is applied to release the ball, because I found 120VAC to the valve for just a moment once the circ pump started running (with top solo option selected), which leads me to believe that the TSV is powered for just long enough to release the ball once there is enough water pressure to hold it against the TSV outlet,
So, I've diagnosed this as a bad TSV because the ball is always free, and that's what I've ordered. I just want to verify that with you guys to be sure I've not misdiagnosed this and actually have a problem with the electronic. See TSV description and schematic below. Please forgive my long winded description.
F21 indicates a long drain time. You'll need to check a few things. Suds - what type of and how much detergent are you using? Excess suds will cause this error, far and away the most common cause of all kinds of drainage issues (see HERE for why). If no suds, check the condition of the drain pump impeller, if the trap was clogged the impeller may have been damaged. Check the pressure switch tube for clogs down where it connects to the bellows that goes to the pump. If that is gunked up it could cause this problem. And of course, check the whole length of the drain hose for blockages.