Fitment is perfect as this is an OEM part. I had previously installed the equivalent Denso branded sensor, seeing that it had good reviews. Not only did it not fit properly (rubber tubes in the wrong spots), but the check engine light came back within 50 yards of driving, so it did not work. I installed this OEM Honda sensor and the check engine light has not come back 200 miles later, so it fixed the problem. Honda ECUs are very sensitive and need the proper signals from these sensors, so don't cheap out or you may regret it. An OEM Honda sensor will always solve the problem the first time.
Can't go wrong with OEM, especially for this price
Works great in my 2005 Honda Civic 1.7 VTEC. The OEM sensor lasted me 10 years and 200K miles and since it failed I have gone through 3 Denso sensors, for whatever reason they just didn't last like the OEM one and would intermittently set a P0134 code. With American Honda dealers charging $600+ for this sensor and my bad luck with the best of the aftermarket sensors, buying an OEM sensor from Japan for less than half price was the only option.
If you have an 04-05 Civic with the VTEC engine and you need to replace your upstream oxygen sensor, I'd recommend that you get an OEM sensor if you plan on keeping the car based on my experiences with the Denso sensors not lasting nearly as long as the original sensor did.