HP LaserJet Enterprise 500 Color MFP M575 - Manual (Page 71)

Print when a toner cartridge is at estimated end of
life
Low This message displays when a supply is nearing the estimated
end of its useful life. is the color of the supply, and
is the type of supply.
Very Low This message displays when a supply is at its estimated end of
useful life. Print-quality problems can occur when using a
supply that is at its estimated end of life.
ENWW Print when a toner cartridge is at estimated end of life 55