still p0401

[jlaley]

Please help me understand how this EGR system is supposed to work. It's a 2000 Camry with 4 cyl. and 125k miles. I have now replaced all three components. VSV first, modulator second and even though it seemed fine, the EGR valve last. Light was back on in about 6 miles. I have checked vacuum lines for leaks and can't find anything. What is the purpose of the modulator and all the hoses? What is supposed to have vacuum and when? This is driving me nuts and it needs to be inspected. PLEASE help me here. Am I barking up the wrong tree with this p0401 code? Can it relate to other things beside EGR?

[71Corolla]

The EGR downpipe (what goes into the bottom of the EGR valve) could be clogged, did you check that? The VSV for EGR, did you replace with a Toyota part? What about the other components? The connector or wiring going to the VSV could be damaged. And make sure the vacuum lines are hooked up correctly.

[BamZipPow]

Did you clean the EGR tube? If it's clogged with carbon...replacing all those components won't do squat.

Did you do the EGR VSV tests? Did test all the vacuum lines vs just looking at them?

[71Corolla]

camrystuff.com, go to the gen4 and take a look at the Emission Control PDF, it has some good testing procedures that will help you out.

[jlaley]

Thanks for the replies. The VSV I got from Autozone. The Modulator and EGR are OEM. I should have gotten OEM VSV too but I needed one, or so I thought, so what are the odds that it made no difference at all? Are you going to tell me I need to get an OEM one now?
The tube cannot be plugged because when I manually open the EGR it kills the engine immediately. That's why I didn't thing a new EGR would fix it but I am grasping at straws so I did. Are there more pieces to this set-up than the three I have replaced?
All vacuum lines that I have checked are fine. I can,t find any leaks. Thanks again for the suggestions.