Secondary air system: Notes

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Fig 1: Identifying Secondary Air System

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Principle

Due to over-enrichment 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 -4- activates the secondary air pump -2- via the relay for secondary air injection -3-. Air reaches the combination valves for secondary air injection -5- and -9-.
The Secondary Air Injection (AIR) valve -6- is activated in parallel, which allows the vacuum to reach the combination valves for secondary air injection -5- and -9-. The appropriate combination valve for secondary air injection thereby opens the path for secondary air to the exhaust channels of the cylinder head.

1 - From air filter housing

2 - Secondary Air Injection (AIR) pump motor -V101-

Component location. See Figure
Removing and installing. Refer to Secondary Air Injection (AIR) pump motor -V101-, removing and installing

3 - Secondary Air Injection (AIR) pump relay -J299-

Component location. See Figure

4 - Motronic Engine Control Module (ECM) -J220-

5 - Combination valve for secondary air injection (right)

Component location. See Figure
Checking. Refer to Combination valve for Secondary Air Injection (AIR), checking function and proper seal
Removing and installing. Refer to Right combination valve for secondary air injection, removing and installing

6 - Secondary Air Injection (AIR) solenoid valve -N112-

Component location. See Figure

7 - Check-valve

Installed position (light/dark side): Arrow points in direction of flow, as shown in .

8 - To Intake manifold

9 - Combination valve for secondary air injection (left)

Component location. See Figure
Checking. Refer to Combination valve for Secondary Air Injection (AIR), checking function and proper seal
Removing and installing. Refer to Left combination valve for secondary air injection, removing and installing

10 - Vacuum reservoir

Installed location: Under wheelhousing liner in left front wheelhousing