On the 7th. gen. 4 cyl. NGK downstream Denso upstream was OEM. Sometimes just replacing the O2 sensor isn't enough, I always replace with new wires also. I get 150K+ from my new O2 sensors. Using a good fuel injector cleaner like BG44 once in a while helps to keep the O2 sensor contacts clean along with the injectors. Bosch O2 sensors are poor quality, but their fuel pumps are good (OEM on my 04).