Lexmark CX725
This mode allows the printer to load the correct firmware code.
Turn off the printer.
From the control panel, press and hold the 3, 4, and 6 while turning on the printer.
Release the buttons after 10 seconds.
An “Invalid Engine Code” error message indicates a problem with one of the internal operating programs of the printer. The printer is not able to receive, and process print jobs until the printer is reset.
: Entering Sleep Mode Fails and Exiting Sleep Mode is Sluggish or Hesitates for Lexmark CX/CS8xx_72x and XC/Cxxxx