F07 indicates a faulty wash heater element or a faulty heater relay on the main control board.
Unplug the appliance and take the rear panel off.
Check the wiring to the heater.
Test the heat erwith a multimeter, should be around 25 ohms.
Take the top off the appliance.
Check the connections to the pressure switch.
Take the thin tube off the pressure switch and blow down the tube as hard and as long as you can, refit the tube.
Check the connections to the main control board (located bottom left when viewed from the rear).
If all of the above checks out ok, you'll need to replace the main control board and have it programmed.
Check these out, see what you find.
Hope this helps
Let me know how it goes or if you need more help
Edited by Fred Bloggs on 1/4/2010 at 8:55 PM EST