Hi Guys,
I have an Epson Stylus CX5300 and recently the Cyan (coloured) ink cartridge was taken out as it needs to be replaced. Just then I tried printing some pages with the printers default settings set to Print black ink only, and an Epson printing message keeps coming up saying I need to replace the Cyan ink cartridge. Why would it say this when I only want to print black? Why won't it just use its black ink cartridge to print the plain black pages of text??

Just then I tried printing some pages with the printers default settings set to Print black ink only, and an Epson printing message keeps coming up saying I need to replace the Cyan ink cartridge. Why would it say this when I only want to print black? Why won't it just use its black ink cartridge to print the plain black pages of text??

Because it doesn't want to run the printer without ink?
The Epson inkjets use an ink catridge as a reservoir and do not directly apply ink from the cartridge itself. It needs ink in the system to keep the litle piezeo pump lubed?

well why doesn't it use the reamining coloured cartidges then to lube itself??

It has to spray a little, I suspect it won't let the other colors spray because it would make color shifts and also pumps air.

It does need the cyan cartridge to be there - in fact you'll likely cause damage if it isn't. The heads on an epson, as pointed out above, are separate to the cartridges - you do not want to get them dry. When the system is running, it will try to use or prepare to use the cyan cartridge (even one that isn't there) which means passing a current through the print head. this means that if there is no ink to keep the head moist, then what is there will dry and block the head. these things are microscopic, so you can't exact clean them with a brush! The epson printers keep a reservoir of ink in each head - if you get a warning message, don't remove the cartridge at 20%, but go and get another one if you will need to continue printing. I usually remove them at 10%, but I make sure there's a replacement immediately to hand - no point messing up a printer for a single ink cartridge.