You need to look at the toner cartrage if it was a new or compatible cartrage bought to replace the old one the problem would not exist unless the printer is broken.(Or if the replacement has a missing or broken or miss postioned counting gear.)
Thier is a counting gear on the left side and on new or replacement cartarages it is in the 11 oclock postion when it is new. When the toner is all used it moves to the 3 oclock postion. What you need to do if you refilled the toner from a refill kit is to manually move the gear.
I believe thier is two ways to do this one buy a reset gear tool.
The other way that I do is to remove the three screws carefully that holds all the gears in place. Dont worry as it is just the cover and you can not really break the cartarage unless you strip the screws.
Once opened manually using your hand push firmly on the counting gear until you move it back to the 11 oclock postion. Then carefully reassemble the cover.
Once you place the cartrage back in the light will go off on its own and the toner counter will be reset.
Do not try to only move the counter without refill you may get a few pages but this is bad for the printer
Do not leave any toner in the cartrage when refilling as this contaminates the toner and really shortens the refill life, try to get all the toner out as possible before refill.
Do not keep reshaking the cartrage and place it back in the printer, everytime you insert the cartarage the it can snag or be inserted a tiny bit wrong and break the gears in the printer. Do so in emergencys only, the rest of the time just refill the toner. $10 with delivery on ebay