Check engine light P0401?

I have 99 Camry i get a check engine light, I Diagnoised in Autozone with "P0401-"EGR System fault (Exhaust Gas recirculation). What is this means?|||Could need to repair the vacuum hoses to have proper vacuum to actuate the EGR valve.|||The EGR valve or one of the components are bad start with EGR and go from there You also have a PDFE censer that is possible cone bad Follow the little hoses going to EGR and you will find it , hope this helps|||p0401 exhaust gas recirculation flow insufficient, it means that there is a blockage in the plumming for the egr.it can pass enough exhaust through the valve. the fun part is finding the restriction. it could be in the eqhuast manefold itself, the pipe between the manefold and the egr, or between the egr and the intake manefold. at the same time toyota does( or at least did) something strange to the egr system. there is a valve in the system that basicly shuts odd the egr, if there is too little or no presure in the exhaust. you may check into this idea. of course the vehicle that i was informed of this idea on was also a nightmare for toyota, a 3 barrel carburator that was just having so many problems marketwide.