In order to "wake" the printer after being in sleep mode for more than 8 hours, the printer must be restarted.
Solution
In order to qualify for the "Energy Star" certification, the printer must power down after being in sleep mode for more than 8 hours.
If you do not wish to have to perform a restart after the printer has been in sleep mode for more than 8 hours, you can set the Shut Down Timer to "OFF" (the default setting is "8 hours").
To change the Shut Down Timer, follow these steps:
On the Tab Selection screen of the Control Panel, press or to select Settings/Adj. tab ( ).
Press the OK button.The Set./Adj. Menu is displayed.
Press or to select System Setup, and then press the OK button.
Press or to select ShutDown Timer, and then press the OK button.
Press or to select "OFF", and then press the OK button.