thanks LL,
I should have FIRST read all the useful past info posted here at this site regarding this problem with other members. They support and agree with your assessment. A lexus technician even mentioned doing a 'smoke' test but I don't have access to that kind of equipment. The general resolution was replacing the charcoal cannister that already comes with valve attached to it but can be sold sold separatley. I priced a OEM cannister and attached valve at $300 and change, including shipping and handling from an ToyotaParts.com (I belive.) Several mentioned that this resolved and took care of the PO446 problem. It was also posted and mentioned that the exhaust system does not need to be completely removed to access the old and install the new cannister on the passengers side underneath my es300....very good stuff. The last charcoal cannister on my previous 1997 ES300 was about $700. including labor from my mechanic. Doing this myself sounds much better. I'll post back later when I get the part and hopefully positive results.