The black colour can look different  (slightly less deep) than the original. This has to do with the ink, but does not harm the printer.

If the black really looks grey, it can also be due to the printer settings:

Check the paper settings. This should be set to “plain paper”. If the paper set is to “Glossy” the print turns to grey. To change the setting, click on Control Panel> Devices and Printers> Select the printer and click the right button> Printing Preferences> Tab: Paper / Quality> Media: Plain paper