⚠
warning HP
Error Code Toner light
Indicates that the print cartridge toner level is low.
? What Causes This
Low toner in a black or color print cartridge.
✓ How to Fix It
Replace the corresponding black or color print cartridge and continue printing.
Source: page 7 of the official manual
From the manual
This error code appears in:
HP Laserjet Pro M1536DNF Multifunction Printer