Hi all, have had issues with my 02 plate GX (yep turbos are too much for me to handle  ) which long story short I've narrowed down to being pre-cat o2 sensor - problem is all the tech manuals i can find are fairly vague about parts for the GX (it looks like it's the b*d child of every other model in the range!) so I can't quite work out the part number for the front lambda - any ideas? the ones suggested always seem to have the wrong connector (mine has a white box shaped connector) any help much appreciated 

Looking here should help.

http://opposedforces.com/parts/impreza/

 

O.

Try looking up an Air/fuel ratio sensor instead. Not sure if Subaru was using them at that point but they are much more accurate and generally better suited for use in turbo engines, vs a standard oxygen sensor. They cost more too.