P0401 1999 Toyota Camry -

Question

were is the egr valve located

Answer 1

P0401 EGR flow insufficient detected

The location of the EGR is at the side of the intake manifold,  There are several cause for the EGR flow to be insufficient one of them would be the EGR vacuum modulator, where its filtering system can become contaminated or damage , the other is the VSV valve. or the EGR valve itself and its hose connection

This is the EGR vacuum modulator, this is the number one cause when the EGR fails to operate as intended.

This here is the VSV valve. without this valve properly operating the EGR will not work properly.