To pass emissions during the first 30-60 sec on start up, Subaru used an air pump to push air through the exhaust manifold into the catalytic converter, warming up the cat quickly. The air pump is susceptible to ingesting water causing the air pump valves to rust. If your lucky the valve rusts closed, you just get a check engine light. If the valve rusts open, you get a check engine light and exhaust fumes into the engine compartment.
Valve one is not to difficult to get to - remove; air pump, fuse box, inter-cooler
Valve two is a pain to get to - remove all for valve one plus intake manifold (which requires a bunch of other things)
Each valve runs $350 add labor and your looking at $2500-ish every 30-90k mile depending on how dry an environment you are in. My dealer said I was luck at getting over 90k and they do about 3 air pumps a month, in the high desert.
Subaru redesigned the system to remove this in later model years.
search "Remnex's How-To Series: Air Pump Removal" for detailed instruction for STI only, the WRX has a second valve that is not mentioned.
A D V E R T I S E M E N T S
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To pass emissions during the first 30-60 sec on start up, Subaru used an air pump to push air through the exhaust manifold into the catalytic converter, warming up the cat quickly. The air pump is susceptible to ingesting water causing the air pump valves to rust. If your lucky the valve rusts closed, you just get a check engine light. If the valve rusts open, you get a check engine light and exhaust fumes into the engine compartment.
Valve one is not to difficult to get to - remove; air pump, fuse box, inter-cooler
Valve two is a pain to get to - remove all for valve one plus intake manifold (which requires a bunch of other things)
Each valve runs $350 add labor and your looking at $2500-ish every 30-90k mile depending on how dry an environment you are in. My dealer said I was luck at getting over 90k and they do about 3 air pumps a month, in the high desert.
Subaru redesigned the system to remove this in later model years.
search "Remnex's How-To Series: Air Pump Removal" for detailed instruction for STI only, the WRX has a second valve that is not mentioned.
- michaelshibley, Lancaster, CA, US