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Old 07-01-2010, 10:51 AM   #1
Scooby Newbie
Member#: 232444
Join Date: Dec 2009
Default CAT efficiency code- suggestions for replacement?

I a getting the "Catalytic Converter is below efficiency threshold" code on my wife's 2001 2.5l outback. I have cleared it a couple times (in case it was a fluke), but it has came back. I figure that I am going to need to replace it. I was curious, would it possibly be cheaper to get a generic high performance cat? I figure if it even helps with gas mileage a little bit, it'd be worth it. She commutes almost 100 miles a day in that car.

Any other suggestions?
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Old 07-01-2010, 11:09 AM   #2
Scooby Specialist
Member#: 151079
Join Date: Jun 2007
Chapter/Region: MAIC
Location: College Park, MD
2005 2.5RS RBP
too many friction losses


I've seen research on these boards that suggest that the stock cats are perfectly fine, other cats (or lack thereof?) don't free up any significant amounts of power.

Could this also be a rear o2 going out?
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Old 07-01-2010, 01:38 PM   #3
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Member#: 201277
Join Date: Jan 2009
Chapter/Region: MAIC
Location: Arlington VA
2009 Legacy GT



i used this one in a 2002 Legacy 2.5L EJ251 same as yours been running fine for 16 months now
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Old 07-01-2010, 03:01 PM   #4
Scooby Newbie
Member#: 232444
Join Date: Dec 2009

Well, turns out that today, when I went to check the code one last time... it came back different. Now I got a 133- b1s1 o2 sensor slow response.

Any thoughts on that. I'm going to go search...
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Old 07-01-2010, 07:20 PM   #5
Scooby Specialist
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: Central Floriderp

no symptoms while driving?
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