The Whirlpool Cabrio Washer F1 error happens when the electronic control board detects an out of range pressure signal. There is really not much troubleshooting involved with the F1 error, so just do the following:
Check the water pressure switch hose at the main control board and make sure its connected properly. Then check and make sure the hose is not pinched or kinked anywhere.
If the hose checks out ok and you keep getting the F1 error then you will have to replace the electronic control board to fix it.
You can order the replacement control board from this link - click here to order control board