Can the printer still print if an ink cartridge is expended or not installed?

No. The printer will not operate if any cartridge is expended or removed. It's best to always have extra cartridges on hand.

The printer will display a warning when ink is low. For printers without an LCD panel, when the red/amber Ink light starts to flash, the original amount of ink remaining in the indicated cartridge is low. For printers with an LCD screen, the appropriate warning message or warning picture is displayed to indicate that ink is low. This is a good time to get a replacement cartridge ready for when the cartridge is expended.

When the a solid red/amber Ink light is displayed, the indicated cartridge is expended. For printers with an LCD screen, the appropriate error message or icon is displayed to indicate that an ink cartridge is expended. In this instance, you will need to obtain a replacement cartridge.

Note:
You will not be able to obtain black ink only printing if a colour cartridge is expended, even if other cartridges still contain ink. The printer requires both the black and the colour cartridges to be installed, and with a certain amount of ink in each cartridge to function. Before printing, replace the expended cartridge.

When you send a print job from the computer, a graphical display of the ink cartridge status appears on the Progress Meter window of your printer software. You can also view the ink cartridge status by accessing Epson Status Monitor directly.

Alternatively, if your Epson product has an LCD panel with graphic display you can view the ink levels via the LCD panel menu - refer to your user's guide for information on how to do this.