ℹ
info HP
Status LED blinking with one Ink Alert light on (very low ink)
The cartridge is very low on ink.
? What Causes This
Low ink level in the cartridge.
ⓘ What This Means
Continue printing and replace cartridge when print quality degrades. Press Resume button ( ) to continue, then proceed with replacement.
Source: page 6 of the official manual
From the manual
This error code appears in:
HP Deskjet Ink Advantage 2135 All IN One Printer