9-3 Sedan, Cabrio '04+, Combi, 9-3X Workshop
Dont just leave it dangling
I also saw this when replacing my ignition coils and was unsure where it went. It screws to the bracket that holds the wire harness in the top/back of the engine. There's a void in the bracket for the sensor to fit into, it doesn't fit tight just sets in and screws down.