!!
critical HP
Error Code T1
Incompatible toner installed — not suitable for your machine.
? What Causes This
Use of non-compatible or incorrect toner cartridge.
✓ How to Fix It
Install a Samsung genuine toner cartridge designed for your model.
Source: page 7 of the official manual
From the manual
This error code appears in:
HP Samsung Proxpress SL M4070 Laser Multifunction Printer Series