Hey there, Welcome to the forum!
First off Ade, could you go out to your bike, flick the kill switch off and put the key in the ignition. Then, hold the SELECT and RESET buttons down together and switch the ignition on.
Keep the buttons held down until "DIAG" appears on the display.
Once that appears, you can then release the buttons and then press them down together again to enter the "DIAG" mode.
Once there, you should see a number starting from 01, press either select or reset untill that number goes to 61.
This is where you need a pen and paper handy because next to that 61 will be another number. If that other number is 00 then there is no error code. If however, there is another number write it down and let us know what it is.
If there is more than one fault code, this number may change every 2 seconds to display all the fault codes, write these down as well.
For more information regarding fault codes, look here:
http://www.xt660.com/showthread.php?...ht=fault+codes
Should tell you all you need to know.
Once you've done that, let come back and let us know what codes there are and take it from there!
Cheers.