My Whirlpool double electric oven displays F 0 1 (for large oven) I am unable to turn on large oven when this is displayed. Sometimes, if I turn off the power source and turn it on again quickly the normal display returns and I can use the oven but if I don't use the oven the display reverts to F 0 1 after a short while. Is this a serious fault? One day when I turn off the power etc will the oven not revert to normal settings?