LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Volkswagen >> 2005 >> Touareg 4.2 M >> Repair and Diagnosis >> Engine Performance >> System >> 4.2L - Generic Scan Tool - Engine Code(S): AXQ >> St Generic Scan Tool >> Description And Operation >> Secondary Air Injection System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Secondary Air Injection System

NOTE:

Always replace seals and gaskets.

Vacuum lines and hose connections must not have leaks.

Vacuum hoses must not be clogged or kinked.

For the electric components to work properly, a voltage of at least 11.5 V is required.

Engine Control Module (ECM) is equipped with On Board Diagnostic (OBD).

Components marked with * are tested via On Board Diagnostic (OBD), Diagnostic mode 3: Check DTC memory.

It is possible that the control module will recognize a malfunction and store a DTC during some tests. Therefore the following work steps must be performed in the mentioned sequence after ending all tests and repairs.

Air is blown behind the exhaust valves by the Secondary Air Injection (AIR) system during a cold start. Thereby, the exhaust is enriched with oxygen, initiating a secondary combustion and therefore shortening the warm-up phase of the catalytic converters. Activation is triggered by the Motronic Engine Control Module (ECM) -J220- via the Secondary Air Injection (AIR) Pump Relay -J299- to the Secondary Air Injection (AIR) Solenoid Valve -N112- (change-over valve) and the combination valve.