4,000. The Tzitz Atones

Hilchos Bias HaMikdash 4:7

Just as the tzitz (the plate worn on the Kohein Gadol’s forehead) atones for people who serve in a state of unknown impurity, it atones for the impurity of things that are offered, as per Exodus 28:38: “It shall be on the forehead of Aaron, and Aaron will bear the sins of the sanctified things.” It doesn’t atone for ritually unclean offerings that are eaten or for a person who was rendered unclean by a known source of impurity. The exception to this is when impurity is permitted because of communal need. [This will be explained in detail in halacha 4:12.] In such a case, the tzitz does atone for it.

Hilchos Bias HaMikdash 4:8

The tzitz only atones for sacrificial impurity when it’s on the Kohein Gadol’s forehead, as the aforementioned verse continues: “It shall be on his forehead always, for favor before Hashem.”