Pins from 02 sensor
 

The two pins coming from the 02 sensor going to the plug to motor both look exactly the same. They are unmarked. Can either pin go in each side of the plug ? My car still has a miss while driving and a poor idle. Never ends. Thank you , Nick

There should be a keyway tang that prevents it connect wrongly.

Yes , I see the keyway tangs but the two wires came out of the holder when installing new 02 sensor. Both pins fit into the car plug , does it matter what pin goes in what hole ?

I just read that the two wires are just heater wires so I guess it does not matter.

Have you a photo? Also is there two connectors? On a early O2 or Lamda Sensor, they have one wire. The later use three wire. The added two wires are for an internal heater so the O2 sensor component is up to speed quickly. A photo or two would help.