Hp Officejet Printer Says It's Out Of Ink, But It's Not----why/?

I have an HP Photosmart 8750 that is the same way. I replaced the cartridges about 6 months ago because it said all cartridges were very low on ink. Wouldn't you know, it wasn't even a month before it showed them to be 1/2 empty and they should be replaced. I tried everything. I cleaned the bottom of the cartridges, I cleaned the rails, I even cleaned the spot where the cardridges rest when not in use. Nothing worked. So I am now running them until either the print starts to look dotted or the pictures are too light. So far no problems. It is frustrating, I know, but it is better than replacing perfectly fresh cartridges at $$$ a cartridge.

Try taking the cartridge out clean the contacts if that doesn't work then I wouldn't worry to much about it till you know it's actually getting close, we have a printer that some of the cartridges do the same, not sure if it is in the cartridge itself or the mix between the printer and the cartridge

If it's a color ink or the black ink..it means that you are very low on ink and starting to run out..when you run out of ink, it won't work.