!!
critical HP
Error Code T3
Incompatible or non-genuine toner installed — must be replaced with a Samsung genuine one.
? What Causes This
Use of a non-Samsung, refilled or remanufactured toner cartridge.
✓ How to Fix It
Replace the corresponding toner cartridge with an original Samsung-approved toner cartridge.
Source: page 7 of the official manual
From the manual
This error code appears in:
HP Samsung Proxpress SL M4070 Laser Multifunction Printer Series