HP LJ Pro 4001DN

[TonyP1223]

My HP LJ pro 4001 is not printing 2 sided, I checked the driver and print window on the print job and both say  sided is enabled

[MysteriousMe]

Welcome to HP Support Community, @TonyP1223 

Thank you for posting your query, I will be glad to help you.

If your HP LaserJet Pro 4001 is not printing double-sided even though the settings appear correct, follow these steps to resolve the issue:

1. Verify Duplex Unit Installation

The printer can only perform automatic two-sided printing if the duplexer is recognized.

Open Settings on your Windows PC.

Go to Bluetooth & devices → Printers & scanners.

Select your HP LaserJet Pro 4001 → Manage.

Click Printer properties.

Open the Device Settings tab.

Under Installable Options, make sure Duplex Unit is set to Installed.

Click Apply, then OK.

2. Check Printing Preferences

Ensure duplex printing is enabled at the driver level.

Under Printers & scanners, select your printer → Manage.

Click Printing preferences.

Under the Basic or Layout tab:

Make sure Two-sided printing is set to either:

Flip on Long Edge, or

Flip on Short Edge

Save the settings.

3. Update Your Printer Driver

Incorrect or outdated drivers may disable duplexing.

Visit the HP Support site.

Download and install:
 HP LaserJet Pro 4001 Full Solution Software and Drivers
or
HP Smart Universal Print Driver (UPD)

Restart your computer after installation.

Tip: Avoid the generic Windows "Class Driver" — it may not support duplex printing.

4. Verify App-Level Print Settings

Some applications override system print preferences.

Before printing, in the Print dialog, ensure:

Print on Both Sides / Two-Sided is selected.

Page setup does not disable duplexing.

Check this in:

Microsoft Word

PDF viewers (Adobe Acrobat, Edge PDF viewer)

Browsers

5. Check the Paper Type

Certain media types disable duplex mode automatically.

Make sure you're using:

Plain paper

60–105 gsm (standard office paper)

Avoid:

Thick paper

Glossy or coated sheets

Labels, envelopes, cardstock

6. Restart the Printer & Computer

A simple restart can reset print spooler issues.

Turn the printer off, wait 10 seconds, and turn it back on.

Restart your computer.

7. Test With Another Document or App

Try:

Printing a different file.

Printing from another application.

Printing a test page from Printer Properties → Print Test Page.

If duplex works elsewhere, the issue is document-specific.

8. Consult Printer Control Panel Settings

On the printer’s panel (if available):

Navigate to Settings / Printing / Print Modes.

Make sure Duplex Printing is Enabled.

I hope this helps.

Take care and have a good day.