Lexmark 21S0150 - E 321 B/W Laser Printer Reference page 59

What this light sequence means:
The print cartridge you are using was not designed for your
printer.
What you can do:
Install a print cartridge made for your printer (see
supplies).
What this light sequence means:
The printer is in the Ready mode and Hex Trace is active.
What you can do:
Advanced users can use Hex Trace to help troubleshoot
printing problems. After resolving the problem, turn off the
printer to exit Hex Trace.
Ordering
Continue Cancel
Continue Cancel
59
Ready/Data
Toner Low
Load Paper
Paper Jam
Error
Press Continue
Ready/Data
Toner Low
Load Paper
Paper Jam
Error
Press Continue