So a few weeks back my cel came on so I had my mechanic by with his scanner, it spit off a code for my 02 sensor (the one that plugs under the passenger seat) I had him replace it with a denso o2 sensor but the check engine light came right back on a week later. Anyone know why?

 

2005 Honda Accord ex 4 cylinder

 

What brand sensor did you install. Denso should be what you used.

What was the code thrown. Was there troubleshooting done on the cat and sensor before replacing the sensor