Unknown printhead error
An unknown printhead error occurs when the one of the printheads is causing a problem but the system cannot detect which one it is. Whenever this happens the front panel displays this error message. The number of printheads with unknown errors will either be all the color printheads or all the printheads.
Use the following procedure to isolate the faulty printhead.
1.Select Replace Printheads from the front panel.
2.Open the carriage cover and remove all the printheads.
3.Reinsert the Cyan printhead only and close the carriage cover and the window.
4.Check the front