Product review (3 stars): but the pressure switch seemed like the most likely culprit
After my Duet washer showed a F20 error code, I did some research on the web. There were a couple few things that could cause this code, but the pressure switch seemed like the most likely culprit. I switched out the part and made sure the hose from the pressure switch to the bottom of the tub was not clogged. It worked! The error code disappeared.