We got the trouble code P0401 for our Toyota Camry 4 Cylinder 2.2L engine.
My mechanic said first we have to clean the EGR Valve and since it’s removed we’ve cleaned the throttle body too. After checking the EGR is functioning,we put everything back.
Check the vacuum lines and make sure there is no leak!
After that service engine light came on after 4 miles with the same code.So we decided to replace the EGR Control Vacuum Switching Valve Solenoid VSV. At the dealer we paid $68.After replacement and 5 more miles,the service engine light came back with same code.
My mechanic decided to change the EGR Valve Modulator.($19 on Ebay) Looks like it was stuck open.We’ve reset the code and the car drives fine with no problem.


EGR Control Vacuum Switching Valve Solenoid VSV


EGR Valve Modulator


EGR on the right ,EGR Valve Modulator on the left