I don't see an IST ignition listed for a 2002. Take a look at this link. Which one do you have.
Since it's a carb bike, the error code must be ignition related. It must use a
map sensor for spark advance. The error code may even be erroneous since the ignition system is no longer HD. Need instruction manual for ignition to know for sure.
Pick the one you have if it's listed:
S&S Cycle | Ignition Systems