Secondary Air System, Checking

Secondary Air System, Checking

The secondary air system is designed to enable the catalytic converter to heat up and reach its operating temperature more quickly after a cold start.

Principle of operation
Due to extra mixture enrichment during the cold-start phase, an increased amount of unburned hydrocarbons is present in the exhaust gas. The secondary air system improves the oxidation process in the catalytic converter thereby reducing toxic emissions. The heat generated by oxidation accelerates the "light off" of the catalytic converter and significantly improves exhaust gas quality during warm-up.

Function
- After a cold start, the engine control module - 6 - activates the secondary air injection pump - 1 - via the secondary air injection pump relay - 5 - , and air is fed to the secondary air combination valve - 3 - .
- At the same time, the system activates the secondary air injection solenoid valve - 8 - which supplies vacuum to the secondary air combination valve - 3 - . The relevant combination valve opens a passage for the secondary air injection system to supply air to exhaust ports in the cylinder head.







1 - Secondary Air Injection (AIR) pump motor V101
- Location
2 - Air cleaner
3 - Secondary air combination valve
- Location
4 - Non-return valve
- Installed position (light/dark side and direction of arrow): as shown in illustration. Arrow indicates direction of flow.
5 - Secondary Air Injection (AIR) pump relay J299
- Location
6 - Engine Control Module (ECM) J220
7 - Vacuum reservoir
- Location: in front left wheelhousing behind wheelhouse liner
8 - Secondary Air Injection (AIR) solenoid valve N112
- Location
9 - Cylinder head







Location of Secondary Air Injection (AIR) solenoid valve N112
- Under intake manifold
1. Recirculating valve for turbocharger N249 (green connector)
2. Secondary Air Injection (AIR) solenoid valve N112 (brown connector)

NOTE: The illustration shows a removed intake manifold viewed from below.







Location of Secondary Air Injection (AIR) pump motor V101
- Front right in engine compartment below air cleaner housing







Location of Secondary Air Injection (AIR) pump relay J299
- 3-way relay carrier in electronics box in plenum chamber, position 2

1. Engine control module
2. Secondary Air Injection (AIR) pump relay J299
3. Motronic ECM Power Supply relay J271
4. Fuse S130 for secondary air injection pump







Location of Secondary air combination valve
- Right rear on cylinder head