Hotpoint wf840 displays error code f-10 I have

power off. Check the pressure switch - a round item about 3 inches across with several wires connected, it sits under the top cover. Its an air operated switch which tells the machine water has reached the correct level. Disconnect the thin rubber pipe from the switch and blow down through it to clear any blockage. Switch itself may be faulty but its more likely the pipe is blocked.
Also check the filter - generally located behind a panel at the foot of the machine.Some are obvious like little square hatches and some are hidden behind the trim panel at the foot of the machine. Once panel is removed the filter will be seen. Its a circular fitting which generally unscrews in an anticlockwise direction.

These codes are the sickness of these hotpoint machines. I have exhausted so much time diagnosing them. I don't remember the codes anymore, but I remember using the manual to see what the code means, and see if indeed it was the problem. It all came down to getting a new electronic circuit board for these machine. Being an electronic technician it is easy for me to determine that indeed the electronic controls is the problem. This should be a recall on these machine. It seem that the electronic controls malfunction right after the warranty expires. I know one thing I will never buy one of these machines after working on them because I will go as far as read the program in that chip and see what they put in there. A programmable chip can be programmed to do something months later. They all seem to have the same problem of displaying codes later in its usefull life. A technician will do the same thing as order the circuit board. Heck you can replace that yourself it is not even hard to replace at all. The problem is the electronic circuit, and needs replacing.