HP LaserJet M405n Pro
Diagnostic. Perform an engine test
When the engine test is performed, a test page with horizontal lines prints if the engine is functioning correctly.
To perform the test do one of the following (with the printer in the Ready state):
Simplex printers:
Depress and hold the cartridge door release button, and then open and shut the cartridge door three times within a three second time period. A single-sided test page prints.
Duplex printers:
Depress and hold the cartridge door release button, and then open and shut the cartridge door four times within a three second time period. A double-sided test page prints.
NOTE: A single-sided test page prints if the duplex function is disabled.