Hi Kelly , F-03 means that the NTC (Negative Tempature Co-efficient) is open or short circuit . And in English that means the device that regulates the water temp is either faulty or the wiring has come off . This device is attched to the heat element at the back of machine (depening on the age of the machine). check for loose wires . failling that you may need and new control board.
Dee Jay
March 2006