What does the error code F01 mean on a Duet washer?

Unfortunately the F01 code is the main control board failure. You can try a reset by turning off the breaker for the washer, leaving it off for a few minutes and then turning it back on. Otherwise you can look on EBay for a board, have a tech troubleshoot it or , if the washer is more than 7-8 years old and used frequently, get a new washer. The less "bells and whistles" the better.

You do not need a new control board. Just solder the one in the machine: https://www.youtube.com/watch?v=6RHJj35VGk4 then https://www.youtube.com/watch?v=JRw_0eGkMAs This is a very easy thing to fix and a common problem.