Toyota Repair: fix for code 401 2000 toyota camry 4 cyl., vacuum hoses, egr valve

Question
2000toyota camry 4cyl.code401 modulator valve & egr valve replaced no help. there is vacume at egr valve at 2500 rpm. when vacume applied to egr valve at idle , engine runs rough, as it should.

Answer
Hello, a very common problem on these engines for the P0401 code is an intermittently working EGR vacuum switching valve (VSV) it's located under the intake manifold near the front of the engine mounted to a small bracket, it has two vacuum hoses and an electrical two wire connector, try replacing it.