DGIKULJOT

Hey guys,
I hate to keep creating new posts but this is one of my last issues with my car. I keep getting the insufficient EGR Gas Flow code, po401 I think. I have cleaned my EGR valve 2 times and verified it works properly many times with a Vaccum pump as well.
I replaced the EGR VSV with a slightly used one since I accidentally broke the original one while trying to pull the vaccum hose off . On the used VSV the resistance is within spec and the solenoid does opperate when connected directly to 12v. I have also tested the vcv according to my Haynes manual and it seems fine as well. Also the resistnaces for the intake air temp sensor and the egr position sensor are within spec. What I noticed today was when i took the vaccum line off of the egr with car started I couldnt feel any suction being created.

So I guess my question is when exactly does the ECU send pulses to the vsv to operate the egr valve? Is it during specific conditions or should there always be vaccum going to the egr? I am suspisious that maybe the signal isnt reaching the vsv and that is creating a lack of vaccum to the egr. Thank you so much guys!!!!!!!!

LeX2K

My advice is to replace the VSV with a brand new one and go from there. I'm ran into this problem several times, the VSV tested good but the code kept coming back, meaning the VSV operation was intermittent.

hzt30

Vacuum is applied to the EGR valve at certain engine load conditions as determined by the ECU. Vacuum should not be applied to the EGR valve at idle. Usually, with the engine warm and you do a snap throttle the EGR valve should operate.

P0401 states that after the engine is warmed up and run at 80 km/h (50 mph) for 3 to 5 min. the EGR gas temperature sensor valve does not exceed 35°C (95°F) above the ambient air temperature (2 trip detection logic)

Possible causes:

>EGR valve (stuck closed)
>Open or short in EGR gas temp. sensor circuit
>EGR gas temp. sensor
>Open in VSV circuit for EGR
>
VSV for EGR

>Vacuum control valve

>Vacuum hose disconnected or blocked

>ECM

DGIKULJOT

I am probably going to do that, did just replacing the vsv work for you? What amazes me is before I always had the code po446 but never had Po401. When I chanced the canister vsv and some vaccum lines that code went away. That was when I broke the original egr vsv and bought a used one that supposively only has 40k miles on it. Maybe it does readomly cause problems and thats why all the egr problems started.

Did you have any super cheap source for that vsv or Should I just shell out like 50-60 dollars at a auto parts store?
Thanks.

P.S. I have learned so much about vaccum systems while working on this car

LeX2K

I have not replaced it on my car, but have on Camry's. I used an original Toyota part, the aftermarket ones never seem to be any good. You don't have to get it at a dealer necessarily. I'm not saying it IS the VSV, but what happened to me is I eliminated all other possible causes, and thought the VSV was good because it passed testing, but replacing it cured the code. Perhaps you are in the same situation, but make certain the top and bottom ports on the EGR valve are not clogged, although it sounds like you've cleaned them well.