Canon PIXMA MP450 User Manual page 86

When the "?" mark appears on the Low Ink Warning
If you install an old FINE Cartridge, the "?" icon appears for the FINE Cartridge in question. In
this case, the remaining level of ink cannot be calculated correctly.
If you try printing when "?" mark appears, the following message appears and printing stops.
OR
OR
In either case, clicking [OK] cancels the error indication and enables continuation of printing.
However, the error detection function is disabled after the error indication is canceled, therefore,
Low Ink Warning message does not appear later on. When you install a new FINE Cartridge, the
Low Ink Warning is enabled automatically.
84 Chapter 10
Routine Maintenance