Whirlpool has a monopoly on the front load washer market. The Duet, Duet Sport, He2/3/4/5, are all made by Whirlpool. The error code F35 is very common on these front load washers. F35 means that the pressure switch thinks the tub is overflowing with water. The fix is to replace the washers pressure switch. The pressure switch is located on the top of the washer. To access remove the three screws that anchor the top down. The pressure switch is held into position with a plastic clips. Pull the switch or use a flat head screw driver to remove. Depending on the serial break, the pressure switch may have several wires going to it or a wire harness with several wires going to just a single plug.
Before you order and replace the washers pressure switch, make sure the hose that connects to it isn’t clogged. Often times sediment will get clogged where the hose connects to the rear of the tub and F35 will appear on the washer LED screen. You can purchase Whirlpool Duet and Kenmore HE parts by entering your model number in the search box. If you have further questions, you can post your question in the Whirlpool Appliance Repair Forums.