You can check the level of remaining toner according to the following, whenever you want to. It is recommended that you check the level before you start to print a large job.
<Device Status> <Toner Level> Check the toner level
Toner Level Messages
<OK>: There is no need to replace the toner cartridges.
<Low>: The toner is low. Make sure that you have a replacement toner cartridge ready.
<Device Status> 
Toner Level Messages