Laser printers use special toner cartridges that have smart chips installed on them. When the printer runs out of toner, the smart chip recognises the low ink status and sends a warning to the printer. The printer then sends a message to the connected computer, and that's how you know when to change the cartridge. However, instead of changing the cartridge, many people prefer to refill the existing cartridge. After refilling, you must reset the toner chip so it recognises the refilled ink level using a specific tool that can be bought from a printer accessories store.
Buy a chip resetter specific to your laser printer cartridge. A resetter is a tiny plastic tool, which when brought into contact with the printer's chip, resets its memory.
Place the cartridge in an upward position on a flat surface. The release points on the cartridge should be pointing in the upward direction. Hold the resetter upright, making sure its LED lights are also pointing upward.
Push down all the pins on the resetter. Depending on the model, there may be a button instead of pins.
Keep pushing the pins/button until the LED light on the cartridge turns green, or it indicates with a beep that the cartridge has been reset. The entire procedure shouldn't take more than five seconds.
Open the printer tray and place the cartridge back into the printer. The cartridge is now ready for use.