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Old 01-13-2003, 11:59 PM   #5
Scooby Newbie
Member#: 7711
Join Date: Jun 2001
Chapter/Region: SWIC
Location: Tucson, AZ
2005 WRX STi


I recently had a P0420 (cat efficiency low, bank 1) on my 00 RS. I have a Stromung 2.25" cat-back, Borla headers, and 47K miles. The mechanic i went to (Honda and Subaru specialist) says he sees these types of codes alot in cars with high-flow exhausts and headers. A lack of heat shielding on the headers can supposedly also cause this, since the exhaust loses too much heat before getting to the cat.

I was told this will cause no harm, but the cats may not be working as well as they could.
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jeddy is offline   Reply With Quote