Bergerb

[Bergerb]

2001 Legacy GT. 

Cel comes on, O2 sensor below threshold. Replaces O2 sensor 1 & 2, replaced cat. Cel comes back on every 6 months the cel comes on with same code. Now it comes on then goes off about once a month. 
I’m stumped. 

[brus brother]

I think in 2001 generation you can use a spacer to back the 2nd O2 sensor out of the stream if you are getting P0420 code.

Seems you have done everything possible. Are you using genuine subaru parts?

Check out Cardoc on subaru ouitback forum. Here

If you give him live streaming data, he often helps with diagnosis where repair by wallet has failed.

There are 2640 posts on this thread so, you are not alone. Have fun reading.

If you want, i have one of the drilled out spacers that I can mail to you.

I sold my 05 OB after driving for 8 years with the code and sliding through emissions with a trick or two. The spacer wouldn't work on the 05.

[idosubaru]

3 hours ago, Bergerb said:

2001 Legacy GT. 

Cel comes on, O2 sensor below threshold. Replaces O2 sensor 1 & 2, replaced cat. Cel comes back on every 6 months the cel comes on with same code. Now it comes on then goes off about once a month. 
I’m stumped. 

Post your actual code(s). P???

Any other codes, or just one?

Check for vacuum leaks and all vacuum hoses around the intake manifold, air filter, air intake hose.  PCV system hoses are prone to cracking. 

Is it getting reasonable gas mileage and driving okay?

[1 Lucky Texan]

exhaust leaks can be a problem too.