'04 TL 02 Sensors?

I have done a search and get mixed reviews... Replaced the 02 sensors in my GF's 04TL (automatic trans) about 3 mo ago.. The CEL has never went out..? I have a scan tool and it continues to show 02 sensors? well, it is time for her to get the car inspected and we need to clear the CEL... SO, the dealer says that we must use the DENSO 02's... I have looked everywhere for these.. Please tell me the best place to get them (other than stealership) with part numbers please. There are only 2, correct?
Thanks in advance....