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Home >> Audi >> 2014 >> TT Quattro Base, 2D Convertible >> Repair and Diagnosis >> External Pages >> Different car >> Section 55 (3.2L - Exhaust System, Emission Controls - Engine Code(S): CBRA (Roadster) (As Of 03.2009)) >> Exhaust System, Emission Controls >> General Information >> Secondary Air Injection System Principle And Function

Secondary Air Injection System Principle And Function

WARNING: This page is about a different car, the 2009 Audi TT and 2008 Audi TT. However, it is still accessible from the selected car via links, so may be relevant.

Principle 

Due to the rich mixture during the cold start phase, the exhaust emissions contain an increased level of unburned hydrocarbons. Due to secondary air injection, exhaust in catalytic converter is reoxidized better and fewer pollutants are given off. The heat released by secondary oxidation shortens the start-up time of the catalytic converter considerably, as well as significantly improves emissions quality during the cold-running phase.

Function 

In the cold-running phase, the engine control module activates the secondary air injection (AIR) pump via the secondary air injection (AIR) relay. The stream of air from the secondary air injection (AIR) pump opens the combination valve and allows air to flow into the exhaust system before the catalytic converter.

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