i have been facing this problem for the past couple of days. i have the p0401 code appearing. i erased it and drove for about 1-2 hours and then it appeared again! am not getting whats wrong although i checked all the line going to the egr and they r in place. i beleive if the lines were loose it should have shown me the code directly the min i drive the car not after like a couple of hours.and sometimes i used to drive it park it and then after driving it again the code appears! any ideas?
10x!

 

So u made sure the EGR line under the intake manifold is not loose? Re-check them again and zip tie it

 

they r not loose and u cant easily unplug them but i didnt ziptie them! they r well plugged!

 

any ideas??

 

If it's not the EGR, then check the EGR solenoid. It's in a horrible place to get at, way down under the intake manifold.
It's the same type solenoid as the boost one.

 

yes check the egr solenoid has three vacum line that go to it way down under the intake manifold above the t case. as for zipties i currently have 3 zip ties on that egr valve line and it still pops of from time to time eventually im thinking super glue lol jk

 

You don't by chance have the JDM MAP sensor mod do you? There was an issue with the JDM MAP sensor causing this code for a while, but it has since been resolved.

 

no i dont have the jdm map sensor!
assume that one of the vaccum lines popped out, then the p0401 fault code will always show, even if i erase it! bec the min i drive a fault error will be read! right?
if thats the case then i dont think its vaccum line problem, bec after i erase the fault code i drive it for a while after the light comes on!!
so whats do u think by this??

 

one of the nipples broke off on the egr solenoid on my car and i had to replace it. get under your car and visually inspect the solenoid, its on the braket that holds up your intake manifold

 

did the same yesterday as my egr valve electric connector broke! the only available i found at the time was from an EVO VIII.... Today got the same code again...

Is the EVO VIII and EVO IX valves the same? i noticed that my original valve was metallic and the VIIIs plastic.... could this cause a problem?

 

ok i will check today!
does teh iac motor affects this also??

 

bump!