Hi. 

Please can any anyone help ? I need to replace the o2 sensor in my 2004 2.0 AWD non turbo automatic (74k miles). Everywhere I have searched on-line indicates it should be  3 wire, but the one fitted on the car is 4 wire, see pic..  They price between 25 UKP for a universal  to 200+ for a genuine part.  Can anyone clarify this? Thanks.

Should be a Denso DOX0307 , 4 wire, they about £80
You have fault code ? P0032 ! has wiring to sensor been verified with test meter ?
Would need engine code or reg number be 100%

opie oils does them and subaru owners club members gets 10% discount I believe .

Do not buy any cheap ones as they junk, direct Denso cheapest good ones you will get .