catalytic converter on 2003 Subaru Baja

My car has an aftermarket exhaust system. I am told that the computer says that it is not ready for testing because I only have one catalytic converter instead of the two that came stock. Do I need the two in order to pass a PA emissions test, or is there something else wrong with the car?

by in Philadelphia, PA on August 17, 2009
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2 answers
ANSWER by , August 17, 2009
This is kind of a complicated one. Before you modified your emission system, it had been tweaked and tuned by Subaru to work with your engine computer to produce a very specific emissions result, so that you could pass a state emissions test. Altering the emission system will push you outside of that spec, and you will likely not pass a state emission test because of the change--but it totally depends on the state emissions test and how strict it is. In California, you would almost certainly not pass. Maybe in Pennsylvania. Is your check engine light on? Did your upgrade come with some changes to your engine computer?
ANSWER by , August 17, 2009
My guess is P0420 code.