There are several Youtube videos on solving the F20 problem which was a water flow issue.
I did the simplest and obvious fixes, check the intake water lines, outtake water line and checked the filter basket at the bottom.. All good.
The youtube videos points to three electronic spots, the flow meter; pressure regulator; and the water intake solenoids. All three have a small circuit boards that it nearly impossible to check or repair. Rather than trying to isolate the problem, it was easier to buy and replace all three meters. The installation instruction videos were excellent.
It was a 1/2 hour fix. Most of the time was removing and putting the stuff we had on top of our washer. We had a Kenmore Elite Washer front end. Sorry I cannot remember the model
number/
Appliance Parts Pros had the exact parts. They have an excellent customer service department to take my order by telephone. The delivery was within 2 business days. I purchased the 2 day shipping option. All appliances except the toaster requires shipping and delivery asap.
I did buy an extra hose ($5) just in case, but did not use it.
I was using the washer within 5 minutes of the finished repair, turned the water back on and the power too..