From GE website:
Microwave Error, Fault or Function Codes
Fault codes are programmed in many electronic microwave controls. These codes help GE Service technicians quickly diagnose issues with the microwave.
Fault code Definition
F1 Open Thermal Sensor, due to excessive heat in microwave cavity
F2 Shorted thermal sensor
F3 Shorted touch pad panel
F4 Open humidity sensor
F5 Shorted humidity sensor
F6 Shorted temperature probe.
F10 Shorted Touch Screen on JVM2070
In order to attempt clearing the code yourself, please follow the steps below:
Press CLEAR/OFF or CANCEL.
Program control again.
If the fault code appears again, disconnect power to the microwave for 30 seconds.
Program the cooking function again.
If fault code appears again, service will be required. If you would like to schedule a service appointment, please contact GE Consumer Service or go to http://www.geappliances.com/geac/schdl_rpr/index.htm to schedule a service appointment on-line.
GE does recommend unplugging the microwave until you have it serviced.
If probe appears in the display, make sure probe is firmly inserted in to the wall of microwave and also into the food item. If you are not attempting to use the probe, follow directions above to reset the control.
Also, PF means power failure. Displays this message after it has been unplugged or if there has in fact been a power failure.
DA7, May 2006