Code#PO401- Mitsubishi 2003 Galant 4cyl- indicates problem with EGR- buit it works

Question

Po401 Code- for EGR valve- although it can be operated manually- do not know how to diagnose/repair to pass inspection

Answer 1

P0401 EGR  flow insufficient

Opening the EGR manually and if the engine stumble or stall this means your EGR port is clear. what the EGR has to it, is a vacuum line, at throttle opening (Part throttle ) the EGR should lift, if it does not, this lead you to to either the solenoid being non operation or the vacuum line leaking . If the vacuum line are properly connected and there is no rupture or leaks of the vacuum line for the EGR (use the underhood vacuum route) the solenoid for the EGR is more likely the suspect.Make this a hobby in replacing everytime emmission test comes around.