Duplex printing, prints single-sided with a blank sheet between each page.

[ejohn01]

My HP OfficeJet 4650 recently stopped printing automatic duplex.  Instead, it prints the print jobs single-sided and ejects one blank piece of paper between each page that it prints.  I haven't changed a thing on my system.  No software updates, no new hardware, nothing has changed except this bizarre duplex printing activity.  Any idea how to fix it?

[Echo_Lake]

@ejohn01

Thank you for posting on the HP Support Community.
 

Don't worry as I'll be glad to help, I appreciate your efforts to try and resolve the issue. 
 

Perform a hard reset on the printer and make sure that the printer is connected directly to the wall outlet and not to the surge protector.

• With the printer turned on, disconnect the power cord from the rear of the printer and also unplug the power cord from the wall outlet.
• Remove USB cable, if present.
• Wait for 2-3 minutes, press and hold the power button on your printer for about 30 seconds to remove any additional charge.
• Now plug back the power cable straight to a wall outlet without any surge protector or an extension cord and then plug back the power cord to the printer.
• Turn on the printer and wait till the warm-up period finishes and the printer is idle.

Make a 2-sided copy: 

Make a 2-sided copy from the scanner glass

Make a 2-sided copy from the document feeder

For more in detail, please go through the User guide of this printer and scroll down to Chapter 4. Copy and Scan pages number 21 & 22.
 

Hope this helps! Keep me posted for further assistance.
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