You must manually put the printer into Service Mode (usually by holding Resume and Power in a specific sequence).
Its most common use is resetting the "waste ink" counter, allowing the printer to function again after it stops due to "full" pads. You must manually put the printer into Service
For those who are looking for a direct link to download Canon Service Tool V.4906, here is a suggested link: You must manually put the printer into Service
The primary reason users search for this software is to resolve the dreaded "Waste Ink Pad Full" error (often codes You must manually put the printer into Service