Error Code Red Blinking

A minor error occurred; the machine is waiting for user action to clear.

? What Causes This

Low toner levels, paper jams, open cover, or end of print quality period.

✓ How to Fix It

Consult display message and perform appropriate troubleshooting step. Reload paper, close door, clean jammed areas. If toner low, prepare a new cartridge for replacement.

Source: page 130 of the official manual

From the manual

This error code appears in:

HP Laserjet Mfp M438