Quote Originally Posted by UselessPickles View Post
I don't remember what colors the connectors are on the wire harness side, but those should be obvious based on location. The more forward/upward located harness connector is for the upstream sensor.
I was just looking at mine, and this statement is only true for the passenger side. The driver side wiring harness has connectors for both upstream and downstream sensors right next to each other. The wiring harness connectors appear to be color coordinated to match the color of the connector of the sensor... but remember that when looking at those connections, the sensor connector you see there is the Prodigy extension cable; not the sensor connector itself, so don't trust the color of the sensor-side connector where downstream sensor plugs into the factory wiring harness