Does anyone definitely know what the Lambda sensor's thread spec. is for a 1993MY WRX saloon (GC8A48D)?

I'm certain that the thread pitch is 1.25mm, but what's the thread diameter - is it 12mm or 18mm or 22mm or ...etc.?

Is the hole located in the driver's side header?

Thanks, John.

 

the thread size on mine is 18mm x 1.5, 1995 wrx
i would have thought they would all be the same,
hope this helps