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Old 04-21-2013, 07:28 PM   #1
Scooby Newbie
Member#: 345673
Join Date: Feb 2013
Default STI: Check Engine Light On: HAS DTC PO420

I am having trouble with my check engine light. This is the 2nd time it appear in 2 weeks. I believe it started with taking it to get an alignment. For some reason, they unplugged the battery. I know this because all my radio stations and equalizer was reset.

So I had my car diagnosed and cleared but the light came on again. The first time I took it in the diagnostic reported:

HAS DTC P0420, catalyst efficiency below threshold.

I have an intake, exhaust, down pipe, and Cobb Accessport.

Do I need to reset the ECU using the Cobb Accessport? I'm fairly new to this stuff so would it be better to take it in or can I easily do it myself

Thanks in advance for any help
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Old 06-10-2013, 11:40 PM   #2
Scooby Newbie
Member#: 350123
Join Date: Mar 2013

I've had two subarus with that problem code and both were because of a rust hole in the fuel filler neck. The dirt builds up behind the plastic shield and the neck rots out. Check the fuel system for air leaks, any leaks will set that code. Some epoxy over the hole fixes it.
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