I wanted to post something on this problem because I had such a hard time with it. I kept getting the same "check engine" error that everyone else was getting. I replaced both O2 sensors with both Bosch and Denso brands and the problem kept coming back. I found out by calling the dealer that I had a California emissions engine and that I needed a "special" O2 sensor that costs $330. I took the vehicle to my mechanic and he called a friend of his that specializes on Hondas. He told him that certain Hondas with ULEV VTECH engines do require a special sensor. He suggested that I used Bosch 13493. It worked. Hope this helps someone out.