Ok this week will permit me more time here to read and compare. I read your PM thank you.

Ok I came back to input my positive result. After replacing and checking the culprits in my issue where the VSV and the Modular...I replaced EGR valve only cause crack in housing but can't point a finger at it to...anyway while doing physical simple steps I found out and replaced the VSV with used Ebay part and Modular with junkyard used part off a Avalon similar year same engine...I already explain a simple test one can use to test VSV in prior post in this thread...but to test the Modular remove it (remove 4 hoses 3 top, 1 bottom) take out of bracket and apply vacuum to single big port on bottom of Modular..

P.S. Vacuum can be applied without machine simply place bottom port partially in your mouth and breath in(inhale not exhale)if air does not flow it's presumed part is fine...if it does it's very likely part is bad.

So replaced EGR applied vacuum to hose from exit port from VSV while engine running caused engine to run very rough.
Replaced VSV test post in earlier post.
Replaced Modular testing how to above.

Good-luck forum.

Thanks for all you guys here, I too benefited from all the postings on this forum, it directly resulted in a DIY fix of my P0401 code on a 01 Camry, just to share with you my experience.

P0401 code appeared, reading and understanding of the EGR valve, Vaccum Modulator and the EGR VSV could be the culprit, dealer and repair shop will replace all three at once for about $850 and up. Based on readings from this froum, I did the following,

1. Bought a VSV and had a local shop replaced for me since it requires a lift and it's very hard to reach (paid $50). But code came back 7 miles, same code, checked the one replaced, it's good, as the local shop told me, my VSV is not the problem. The reason I chose to replace it first is based on readings and posting on the 4th gen Camry.

2. Replaced the Vacum Modulator myself in about 5 minutes, reset the code, been driving for almost 200 miles, code never came back, checked with scanner, no code. The part was $65 plus tax.

I think in my case the modulator was the problem, though I had checked upon removal, couldn't find any issues on it, so I put it back and replaced the VSV. Now I have a good VSV in my hand, I checked with multimeter, it shows correct range of resistance and applied 12v, it will click and redirect airflow. If anyone want this EGR VSV (it's a Toyota geniune part 90910-12080, clean, like new), please PM me, I paid $59.99 plus tax for a non-Toyota part.

I spent a total of $60 + $65 + $50 for about $175 plus tax to fix this code, a whopping savings of almost $700 over dealer and repair shop charges, and it's a lot fun too to troubleshoot and get it fixed.

Anyway, just to share with you all my story and hope it will help someone, and thanks again for all your help.

Great job on your fix.

The modulator and VSV do not have specific codes. The codes just indicate too much or too little exhaust gas is being sent to the engine.

You can always try to sell the VSV on Ebay or if keeping the car hang onto it. It is a common issue for it to fail.