I'm putting my 2003 G35 Sedan back together after replacing the valve cover gaskets. Near the end, I have this mystery green wire connector (see image)

Can anyone tell me where that should be connected? I went ahead and put on the air intake and started the car. Everything started fine and ran fine for the minute or two that I let the engine run. Also, there were on check engine lights. Still, I would like to ID where this belongs and plug it in properly.

 

Upper o2 sensor, driver side

 

^^^ He got it for you

 

Thanks, Cux350z. The plate that the other wire was connected to had fallen way down. I had to feel blind for it once I knew what I was feeling for. I appreciate it.