how can i fix error code e602 00003 on canon ir2800?

Hard drive error.
Possible workaround; turn off machine.
Hold down the '1' & '9' keys on the keypad. Turn on machine while still holding the keys. A flashing block will show in the top left corner of the LCD. Let go & leave machine alone for approx. an hour. The message on LCD will read "download mode" when complete. Reboot the machine. The machine may be ok for a while. If the machine did not go to "download mode", replace the hard drive and reload new system software. Layman will not be able to this without the "Service Support Tool".

Freckled legs
January 2012