Yesterday after leaving work I noticed my speedo was going crazy showing random numbers. I bought a new battery last night, checked the speed sensor, the front sprocket nut. Everything was good. WTF could it be?
Im lost. I also checked for codes and it showed-C00 which means no fault.

Hi. The exact same thing happened to me (although it was on
my bandit 1200 which is leaving me tomorrow) and thenthe dash went completely. My dash would just churn out random numbers and sometimes even just show lines rather than numbers.

What it turned out to be was a small weld on the frame eating into the wiring loom from vibration. Eventually found this, filed the weld spot down a tad and re-did the wiring - never had a problem since. Maybe it is your prpblem, maybe not but hope i have given you a place to start. :cheers