2007 Buell Lightning XB12S check engine light

SOURCE: starter location

look on top of transmission behind back cylinder. Same as Harley Sportsters.

SOURCE: torque setting on the rear wheel of a 2008 buell

axle torque is 48-52 ft lbs pinch bolt is 40-45 ft lbs

SOURCE: 2003 buell lightning

It is likely that the cooling fan has died. You can download the program called ECMspy and use your laptop to run a diagnostic on the fan and confirm the check engine light is indeed for the fan. 

Replacing the fan is not hard, but it will require you to lift up the bike by the muffler, disconnect the rear shock, then you can remove the fan.

SOURCE: I have a 2006 Buell Lightning XB12S with 6500KM on

sounds like cable is broken, or clutch bracket is bent or stripped inside the case. I wouldnt think
the clutches would be that worn with only 6,500 on them .

SOURCE: hello i need ecm spy

Americansportbike.com has map for that setup. I have it on my bike also with a Micron/K&N/breather mod, it runs great!

They don't list it on the website, but if you call or email them you can get it.