error code will tell you what's wrong, with FI, ABS, whatever is connected to the bikes brain. If something goes wrong, that you dont' know what the fault is as obvious, then you can plug this thing in and it will tell you what's wrong, if you can get it fix it you can reset the code and ride.
Most of the times if you know whats wrong you can fix it and still go on riding you don't need to reset the code. Its just a tool to tell what's wrong with the bike, without trying for hours to try and isolate or found the problem.
Ya well a flat battery is a flat battery, don't need no tool to tell you that.
