How do I know when an ink cartridge needs to be replaced?

• When the printer's Error light flashes, an ink cartridge is low on ink. This is a good time to make sure you have a new cartridge handy. When the Error light stays on, the cartridge is empty and will need to be replaced. If you're printing from your computer, you'll see a message telling you which cartridge is low or empty. Click the "How to" button to see instructions for replacing the cartridge