Intake valve failure (F02) in dishwasher, anything to try

There shouldn't be any standing water inside of your dishwasher while it is not in operation.

The water could be a few different things, but I would check first to see if water from your sink is being siphoned into the dishwasher. Depending on the install, you will either need a high loop on your dishwasher waste line, or an air gap device.

A high loop basically is when you bring the drain up much higher than the trap in the sink so the water from the sink goes down the drain instead of into your dishwasher. I did this in my own home by fastening the pipe to the bottom of my cabinet before it drops down to the dishwasher.

Your dishwasher may also be defective and is not draining correctly. The pump should be sucking out all of the water from your dishwasher down the drain. There is a possibility that there is something clogging it and preventing it from emptying all the way. Since you already had people out to look at it, then that probably isn't what is causing the problem.

Another possibility is that the sewer itself is backing up into your home. Since the dishwasher is one of the lowest points in your home, the water will go in there first.

There are many ways to skin this cat. But probably the easiest one would be to cut the plastic pipe so that there is no water in it. The reason you want to remove the water is so that you can then use a hair dryer to get the plastic warm and soft. Use two pliers- one to brace the copper valve and the other to twist the plastic pipe or connector off.

If that's not working, a pipe sander or dremel tool (with a cut off wheel) could probably chew through that connector pretty quickly, but I suppose you could also try using a box cutter to cut into the connector (which looks like it will be easy if it's warm and soft). But just be careful to not cut too deeply or you might damage some copper or brass threads. You should cut most of the way through the connector and then maybe use a small flat head screw driver to pry the connector loose.