HP ProDesk 400 G7 SFF Maintenance And Service Manual page 70

Cause
Printer is not turned on and online.
The correct printer drivers for the application are not installed.
If you are on a network, you might not have made the connection
to the printer.
Printer might have failed.
62 Chapter 5 Troubleshooting without diagnostics
Solution
Turn the printer on and be sure that it is online.
1. Install the correct printer driver for the application.
2. Try printing using the MS-DOS command:
DIR C:\ > [printer port] where [printer port] is
the address of the printer being used. If the printer works, reload
the printer driver. To run MS-DOS commands, press the Windows
key + r, type cmd in the Open box, and then select OK.
Make the proper network connections to the printer.
Run printer self-test.
ENWW