When a Whirlpool washing machine displays an F1 error code, this usually means that the control board is having difficulty communicating with the motor. The listed repair techniques have been performed on a Whirlpool Cabrio washer, but it seems that the same instructions can be applied to other Whirlpool models, as well as Maytag Bravo and Kenmore Oasis washers. 

REPAIR TECHNIQUE 1) 
To remove the error display, press Pause/Cancel twice. To fix your Whirlpool F1 error code, you should first try to unplug your washing machine or disconnect power for 1 minute and then plug it back in/turn the power back on. Re-select the cycle and press Start. In some cases, disconnecting and reconnecting power to the unit clears the F1 error code. 

REPAIR TECHNIQUE 2) 
According to some repair companies, a possible cause of the F1 error is blockage inside the pressure switch hose. 

First, unplug the machine, so there is no risk of electric shock. Open your washer. You will need a 1/4 inch screwdriver. There are 3 screws on the back. You need to unscrew them in order to open up the console and to get to where the pressure switch hose is. Verify that the pressure switch hose is hooked up properly. Disconnect the hose and blow through it to verify there is no obstruction. If you can blow through it easily, there is no obstruction. If you listen carefully, you can even hear the air coming into your tub, which should mean it isn't disconnected. If you don't hear the air, the other end of the hose is probably disconnected from the tub, so try to reconnect it. 

If you cannot blow through the hose easily, there is probably a blockage inside the hose. Try to remove it, by either blowing harder or inserting a wire inside the hose. Be careful with the wire, not to damage the hose. 

If you could blow through the hose easily, or you successfully removed whatever was blocking the hose, reconnect the hose and turn the machine back on. Run one cycle and see what happens. If the F1 error is gone, this could be due to the removal of the blockage or simply because of the restart of the machine. 

If you are still getting the F1 error code, the cause of the problem could be the control board – however I highly recommend at this point although replacing the board is a simple procedure to contact either a qualified technician and/or whirlpool themselves as there has been several issues with this error code as well as their control boards and in some cases they are offering discounted and even free replacement parts depending on your model.