Canon CLC5151 Reference Manual page 467

Attach the Finisher to the main unit.
Cause The finisher is not properly connected to the main unit.
Remedy Connect the finisher to the main unit properly.
Scanning has been canceled because the size of originals has changed. Fix the order and front & back
of the last 2 pages, return to the 1st page, be sure to set [Different Size Originals], and try again.
Cause Different size originals are being scanned when the Different Size Originals mode has not
been set.
Remedy Place the last two rejected originals back in the feeder. Make sure that the page order is
correct and that the originals are placed properly. Then, set the Different Size Originals
mode.
Yellow toner is low. Replacement not yet needed.
Cause Toner of the displayed color is running low.
Remedy Prepare the displayed color's toner cartridge for replacement. (See "Replacing the Toner
Cartridge," on p. 7-32.)
Replace toner cartridge. (Black)
Cause Printing is not possible because toner of the displayed color has run out.
Remedy Replace the displayed color's toner cartridge. (See "Replacing the Toner Cartridge," on
p. 7-32.)
List of Error Messages
8
8-75