It are display that toner is empty. printer model Toshiba e-Studio 18

SOURCE: Empty used toner not clearing

you have to go into service mode and reset counter.in your manuel

SOURCE: sir i have toshiba e studio 163 my machine

u have installed a toner that is not original ,,,try to put an original toner ,,,and then try or let this toner get empty and then try the original one,,,,

SOURCE: toshiba e-studio 720 toner low message but bottle

If everything is OK, but the message is still appear, then u can clear it by following below steps:
User Function--> User--> General--> Toner Near Empty Detection -->Yes

SOURCE: Toshiba E-Studio 3511 Check Color Toner Cartridge

there is a sensor above the coloer developer unit clean it or change the sensor

SOURCE: e-studio-232 adding toner problem

change the developer with the new one and change the sensor toner.