Canon imageCLASS MF266dn II User Manual page 542

When to Replace the Toner Cartridge
When a Message Appears on the Screen of the Control Panel or Remote UI
Follow the message on the screen to prepare a new toner cartridge and replace the old one. Print quality
may suffer if you continue using the toner cartridge without replacing them.
For details about the message and how to resolve it, see the following:
A Message Appears(P. 628)
When Print Quality Deteriorates
If printouts show any of the symptoms below, the toner cartridge is near the end of their lifetime. It is
recommended to replace the toner cartridge even if a message does not appear.
Streaks appear
White spots appear
Replacing Toner Cartridge
1
Lift the control panel.
Maintenance
Printing is uneven
Partially faded
533
Toner smudges and splatters appear