Product review (5 stars): It worked!
Over the past couple of years I noticed a good amount of water remained in my dishwasher after the drying cycle was done. It started as just a bit and got worse over time. I could hear the pump was running and could see water dumping into my disposal but it was not properly sensing that there was still water in the basin and would shut off before all of the water was drained. Running the reset function (press and hold the start button for a few seconds) would further drain some of water but still left a lot.  Repeating the reset function would not completely drain the basin - again, it was not properly sensing the water in the basin. I checked all the lines, cleaned the traps, and the problem persisted and got worse.  It was so bad recently that the water left in the basin was not clean and the dishes were not getting clean because the dirty water was not draining out of the dishwasher.

Well...  This Check Valve solved the problem!  The valve is accessible from the inside of the basin (no need to pull dishwasher from under the counter). At the rear of the basin four small hex bolts hold the plastic filter in place and the valve in under the filter. You'll need a pair of pliers to get leverage on the plastic tabs to unscrew the old valve. When I removed the old valve it was obvious that the rubber flap had deteriorated significantly and the valve was not able to make a seal.  This now made sense as the flap had probably been deteriorating over time and the worse the seal, the more water was being left behind.

From what I can tell, this valve, when sealed, opens the drain at the lowest point in the basin. When it is in the open (not sealed) position, it serves as a overflow drain as it sits about 3" above the lower drain.  So the worn seal allowed only some of the water to drain (and not overflow and flood the kitchen) but did not allow the lower drain to open.

Great DIY fix for $13 and about 10 minutes of my time.