HP OfficeJet Pro 6978 Printing Yellow instead of Gray in Grayscale Mode

[nstommel]

I have an HP OfficeJet Pro 6978, and the strangest thing has been happening with my printer. When printing in grayscale with color printing off, it prints shades of gra y in yellow ink. This happens regardless of whether the printer is in color or grayscale mode. On top of that, despite ink levels showing there is still cyan and magenta ink, the printer will not print cyan or magenta, only yellow and black (no gray). Attached is a test image, the first one showing what should be printed and the second one showing a scan of what is actually printed. What should be printed.Scan of what is actually printed.

As you can see, the grey background on the bottom is printed in yellow, and cyan and magenta are completely absent despite the cartridge levels being fine. I have tried driver reinstallation, printer maintenance (clean printhead, fix smears, align printhead), and force restarting the printer by removing power but nothing works. It still prints gray as yellow and ignores the color ink cartridges. Never have I encountered such a strange and frustrating issue. I fear I may have to throw away this printer and buy a new one not from HP. I have no patience for nonsensical issues like this. Still, if anyone recognizes this issue or what to do, I would appreciate it.

[8lives]

The ink is clogged in the printhead.

If you warranty is still valid contact HP support.

[nstommel]

My warranty expired some time ago. Does this mean my printer will no longer work? Do I have to buy a new one?

[8lives]

Yes most likely.

You can try cleaning the printhead manually, youtube has many vids on this topic.