Product review (5 stars): Fixed my F20 on Whirpool Duet
Was getting a F20 code from my model WFW9200SQ03 Whirlpool Duet washing machine. First tried a new water valve since that seemed to be the commo cause when searxhing online. That didn't resolve the problem. I then looked at the pressure switch hoae and saw it was trapped behind the drum. When I moves it and looked it over I noticed it was rubbed to the point of wearing through with a tiny pinhole. So I ordered this house through Prime. 2 days later when it arrived I put the hose on and crossed my fingers that it was the issue.

Prior to the replacement, the washer would stop at the rinse part of the cycle, throwing the F20 code. With the hole, the drum was not building up pressure and allowing the pressure switch to determine that water was flowing in. Have run a few loads since replacement without issue.

Wife is happy again and is quoting Red Green. For those not familiar: "If women don't find you handsome, at least they'll find you handy."

Pic of hose where it shouldn't have been and hole before replacement attached. Check this first if you are getting F20. This is cheaper and easier to replace than the water valve.