recently i got installed a egr valve and the tubing. I used my obd to check for any codes and it reads p0401. Why is still reading that as a problem when there is a new egr valve installed?

Could be any of the following instead of the EGR valve:
EGR Vacuum Switching Valve (VSV)
Open or short in VSV circuit for EGR
EGR valve position sensor open or short circuit
Vacuum or EGR hose disconnected
EGR valve position sensor
Manifold absolute pressure sensor malfunction

Replaced mine a few months ago the egr VSV. Tried replacing egr and did not fix the PO401 code on my camry. About $70 for the part at the dealer.