There is no need to respond to this. I am just posting this to help guys who do a Google search because they are having this problem. I have an 03 Tundra and it was throwing these codes for years. I first replaced all the sensors with Denso's, still had codes. Then I replaced the cats with Walkers, still had codes. Then I went over everything and cleaned everything, still had the codes. Finally I ordered Magnaflow OEM grade cats. I had to order them for a 2002 tundra because they didn't show OEM grade for the 03. Problem solved. I didn't just get the cats, I got the cats and pipes that hook up to my headers. They have the sensor bungs already welded in. I hope I didn't jinx myself by posting this.