Audi Secondary Air Injection (AIR) system, checking

Short Description
The Secondary Air Injection (AIR) system causes the catalytic converter to heat up more quickly, resulting in earlier operating readiness following cold start.

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Content
Principle
Due to overenrichment of the mixture during the cold start phase, there is an increased amount of uncombusted carbon monoxide in the exhaust. Secondary Air Injection (AIR) improves secondary oxidation in the catalytic converter and therefore reduces emissions. The heat produced by secondary oxidation greatly reduces start-up time for the catalytic converter, therefore improving exhaust quality during the cold start phase significantly.
Function
In the cold start phase, the ECM -2- activates the secondary air pump - 12- via the relay for Secondary Air Injection (AIR) pump -1-. Air reaches the combination valve for Secondary Air Injection (AIR) -10-.
The Secondary Air Injection (AIR) valve -3- is activated in parallel, which allows the vacuum to reach the combination valve for Secondary Air Injection (AIR) -10- and the vacuum diaphragm for charge air pressure regulation - 7-. The combination valve for Secondary Air Injection thereby opens the path for secondary air to the exhaust channels of the cylinder head.
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