Hello,
The issue would usually be caused by a problem with the toner cartridge or some toner powder has spilled inside of the printer. You can try reseating the toner using the steps in the link HERE and wiping up any loose toner powder inside of the printer with a damp cloth. You can also inspect the color toner cartridges to see if any are leaking. After reseating the toner and cleaning the interior, you can try cleaning the ITB and fixing assembly.
