and I clarified my dude,for engine 2.3 I4 F23A1, Denso Oxygen Sensor # 234-4620 is for the front up, before the cat and Oxygen Sensor Denso 234-4209 is down after the cat
after a long day, I replaced rear mount. The new mount is so cheap that does not use the vacuum hose adapter. I did not think anything bad would happen, but now I have problems with the rpm and stays fast