Hey there my name is Russ I too own a 2006 Scion xA. I have come into the same problem you posted on here some time ago. My car is throwing the codes P043F, P2401, P2402, P2419. I am very aggravated with this situation since I live in CT. I went to my normal dealership and i had to get a rental for a day. After 5 hours they called me and said my car was "too modified" for them to fix it and to come and get it. I am apart of Sckoitics of New England so during my monthly meet to Mass I had them look at it. It cost me $100 for a diagnostic fee, and these are the codes they gave me. I am out of warranty and they quoted me $775 to replace everything. I was about to loss my mind. I would be more than happy to do this repair myself, since you said you did yours. I somewhat know what I am doing with cars. I would just be scared on the filler pipe cover. Any info you can give me would be greatly appreciated.

Russ