HP LaserJet Pro M521 Multifunction Printer series - Manual (Page 44)

When the product is set to the Prompt option, there is some risk that faxes will not print after the new
cartridge is installed if your product has received more faxes than the memory can hold while the
product is waiting for the prompt to be acknowledged.
Once an HP toner cartridge has reached Very Low, HP’s Premium Protection Warranty on that toner
cartridge has ended. All print defects or cartridge failures incurred when an HP toner cartridge is used
in Continue at very low mode will not be considered to be defects in materials or workmanship in the
toner cartridge under the HP Toner Cartridge Warranty Statement.
30 Chapter 3 Parts, supplies, and accessories ENWW