Epson EPL-N2550 Series User Manual page 190

A controller error or a print engine error has been detected. Turn
off the printer. Wait at least 5 seconds and then turn it back on. If
the error message still appears, write down the error number
listed on the LCD panel (xyyyy) and turn off the printer, unplug
the power cord, and contact a qualified service representative.
Sleep
Printing operations are completely suspended.
Toner Low
The imaging cartridge is running out of toner. If the printout is
too light or faint, replace the imaging cartridge as described in
"Imaging Cartridge" on page 213.
You can continue to print until the Replace Toner error message
appears. Waiting until this message appears before replacing the
toner is recommended as toner may spill during replacement if
toner remains in the cartridge. When printouts become faint, see
"Imaging Cartridge" on page 213 for instructions.
To clear this error, select Clear Warning from the control panel's
Reset Menu. See "How to access the control panel menus" on page
149 for instructions.
Turn Paper XX
The direction of the paper loaded in the specified paper source
(XX) does not match the required paper direction. Turn the paper
direction to landscape.
Unable Clear Error
The printer cannot clear an error message because the error status
still remains. Try solving the problem again.
Warming Up
190
Using the Control Panel