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Secondary air injection (commonly known as air injection) fresh air is injected into the exhaust
Secondary air injection (commonly known as air injection) fresh air is injected into the exhaust stream to allow for a fuller secondary combustion of exhaust gases. When the catalytic converter is cold, air injected at the upstream point burns with the deliberately rich exhaust so as to bring the catalyst up to operating temperature quickly. Once the catalyst is warm, air is injected to the downstream location the catalytic converter itself to assist with catalysis of unburned hydrocarbons.
