Where is O2 sensor NA legacy 91 factory catless

[Alvaro Alonso]

Hi,

My dad keeps telling me the legacy has no cat nor oxygen sensor from factory.
I know for sure it has no cat because it used to run on leaded gas. but is it possible it has no o2 sensor?. I have tried to locate the sensor but the haynes manual diagram has not helped very much.
That's the question, where is it? Can I see it from the motor bay?
Could anyone post any photos?

Thank you all.

[scuzzy]

Hi,

My dad keeps telling me the legacy has no cat nor oxygen sensor from factory.
I know for sure it has no cat because it used to run on leaded gas. but is it possible it has no o2 sensor?. I have tried to locate the sensor but the haynes manual diagram has not helped very much.
That's the question, where is it? Can I see it from the motor bay?
Could anyone post any photos?

Thank you all.

O2 sensors are killed by leaded fuel, so if you had an O2 sensor in (or still do) and had leaded fuel, then it's a dead sensor.

on turbo models they're located in the downpipe, on non turbo's they're located just past the section of headers that merges into one section.

[Legacy777]

If it ran on leaded gas, it's probably a carburated engine that we didn't get in the states, and very possibly doesn't have cats or an O2 sensor.

[Alvaro Alonso]

Well, it is not carburated, it is DIS and I got and installed the MSD-dis2

I have been told the cat was an option back in 1991, and maybe it has no O2 sensor at all.
That I want to find out, so I would like to see a photo from any of your cars showing where the o2 sensor must be.

If this car has no O2 sensor that would mean it runs open loop all the time!!!
What would that mean, poorer milleage than closed loop?

If it ran on leaded gas, it's probably a carburated engine that we didn't get in the states, and very possibly doesn't have cats or an O2 sensor.

[subytech]

if its fuel injected it has to have an 02 sensor, unless its mechanical injection and i dont think many people at Subaru new Mr. Rober Bocsh so I dont think thats an option

[Alvaro Alonso]

Rading the FSM, I discovered that some MPFI models were sold cattless and have no oxygen sensors. They have no autotune functionality in the ECU or it is disabled and are supposed to have an idle Air to fuel ratio adjustment potentiometer which I don't know where is located.

[Legacy777]

Hmm.....that's weird.....but thanks for the update. It's good to know.