Operation CHARM
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Subaru
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2008
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Impreza WRX F4-2.5L DOHC Turbo
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Repair and Diagnosis
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Powertrain Management
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Emission Control Systems
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Description and Operation
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Secondary Air System (From '06MY)
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General
General
GENERAL
The secondary air system reduces harmful emissions by initiating the actuation of the catalyzer early by supplying air to the exhaust port of the cylinder head when the engine is cold started to reburn unburned gas.