Epson EPL-N2550 Series User Manual page 189

Install a new imaging cartridge. See "Imaging Cartridge" on page
213 for instructions.
This error is not displayed when the Toner Out setting is set to
Continue in the control panel setting. When the Toner Out setting
is set to Continue, replace the imaging cartridge if the printout is
light or faint.
Reset
The printer's current interface has been reset and the buffer has
been cleared. However, other interfaces are still active and retain
their settings and data.
Reset All
All printer settings have been reset to the default configuration,
or to the last settings that were saved.
Reset to Save
A control panel menu setting was changed while the printer was
printing. Press the N Start/Stop button to clear this message. The
setting will become effective after printing has finished.
ROM Check
The printer is checking the ROM.
Self Test
The printer is performing a quick internal check.
Service Req xyyyy
Using the Control Panel
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