For the record, the P0401 code is an insufficient flow of the EGR system. You need to clean the orifice at the throttle body and the EGR valve. Hopefully that’ll stop the code.
Note that the EGR’s function is to prevent the cylinder temps from getting too high by allowing a bit of inert exhaust gas to be drawn in with the incoming air. It displaces a bit of the oxygen, cooling the combustion process a bit. The oxygen in exhaust gas is already bound up with carbon and nitrogen, so it cannot feed the fire. An analogy would be closing the vents some in a woodstove, reducing the oxygen availability to lower the flames.