Intro: Tutorial: Change 2004 Honda Civic Downstream O2 Sensor
Learn how to change the downstream (after the catalytic converter) O2 sensor. My Civic Ex was throwing check engine code P0420, which prompted this install. I was able to figure out that it was the O2 sensor rather than the actual cat because the CEL intermittently was coming on and off over about a weeks time. Like I said in my other Air/Fuel/O2 sensor video, Denso parts are cheaper than OEM, but they are basically OEM since Denso makes many parts for Honda's straight from the factory.
Honda part 36532-PLR-A11 Denso part 234-4220