DarkPrinceUK

Hi Everyone, Recently the engine management light on my 2005 Impreza 2.0 GX has come on, we have read the codes and identified that we need to replace the pre cat lambda sensor however finding the correct part seems to be an issue as several different suppliers are offering parts apparently for the car but some have 2 wires, some have 3 and some have 4. As I do not wish to order the wrong part, does anyone here happen to know the correct sensor that I would need to buy? Many thanks,