Remove the rear seat and lift out the storage box. There will be a yellow wire with a female bullet connector (on the right side as you stand behind the bike). I have made up a wire with 2 male bullet connectors on either end, plug one end into the yellow wire, turn on the ignition and within 2 seconds ground the other end of the wire to the frame (non painted part) and hold it there. The FI light will then flash codes at you.
Two long flashes + three short flashes gives fault code 23.
Three long flashes + four short flashes gives fault code 34
etc etc.
Once it's given you all the fault codes it will recycle from the begining again.
To get to stored codes and not just present fault codes repeat the above but instead of grounding the wire once and holding, ground it 5 times quickly and then hold it.
Below are the fault codes: