Thanks for saving me a few tools thrown across the garage. With your right thumb, press down on the plug release on top until you hear a slight click. If you don't, you're worried about pulling too hard on the wires. Visually note how the plug is positioned and orient the new plug in the same way. I have a service pit so getting to the sensor was easy. O'Reilly parts manager says their system shows this part as an O2 sensor. So their are not two different parts. O2 sensor and A/F ratio sensor are the same thing. Lucky my search landed on this post.