this would be the 1st thing i'd check, if its buggered you'll be using alot of fuel, just take it to any subaru specialist workshop & get them to check it

will do, many thanks for your help. Would a buggered o2 sensor cause more black residue coming from the exhaust? i initially thought i had a leak in the plumback hose from my hks ssqv.

if the o2 sensor was stuffed, wouldnt a CEL light come on?

yes

mine didn't throw a cel on my99 model, the only reason i knew was fuel consumption (50km less per tank) & my afr gauge didn't move as it usually did

cheers,

so you had to replace your sensor? fairly sure my o2 sensor is located between the dump pipe and the mid section part.

My rear 02 sensor is causing a CEL. Doesn't seem to make a difference to performance/fuel consumption though. Car has a Verso tune.

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[SIGPIC][/SIGPIC]
Should have bought an STI

im running a verso tune as well, no CEL lights though.

I've gone through 2 rear 02 sensors. Dunno why but they keep popping. Not even sure if i have a front one in the up-pipe? I know i have the resistor mod on my car when the full TBE was install and catless up-pipe.

Perhaps there is still one on the headers.

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[SIGPIC][/SIGPIC]
Should have bought an STI

checked the o2 sensor on sat, seems fine. Any other suggestions?