Manual is a must for any bike owner as much of the maintenance can be done by you and save a lot of money. The FI light is just like your SES light on your car and comes on when you have a sensor problem. Check online as there is probably a way to check the codes yourself and a code table to tell you what it means, probably in the manual as well. Then you can fix it yourself or at least know if you feel comfortable doing so. Bikes aren't that different than cars in their systems, just packaging, so if you can work on your car you can work on your bike just the same if you have the right manuals.