Test sequence

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2005 Volkswagen GTI, 2004 Volkswagen Jetta, 2004 Volkswagen GTI, 2003 Volkswagen Jetta, and 2003 Volkswagen GTI. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

Do not use compressed air during the following check!

Remove engine cover.
Remove intake hose between Mass Air Flow (MAF) sensor and throttle valve control module: → 24 MULTIPORT FUEL INJECTION (MFI)

Fig 1: Locating Vacuum Hose At Combi-Valve

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Pull vacuum hose off Secondary Air Injection (AIR) solenoid valve N112 and combi-valve - arrow -.

Fig 2: Hand Vacuum Pump VAG 1390 Connected To Vacuum Hose From Combi-Valve

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect hand vacuum pump VAG 1390 to vacuum hose from combi-valve - arrow -.

Fig 3: Locating Pressure Hose To Combi-Valve At Connection

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect pressure hose to combi-valve at coupling - arrow - and blow in using light pressure. Combi-valve must be closed.
Operate hand vacuum pump. Combi-valve must open.

When the combi-valve does not open or is continuously open:

Replace combi-valve, - -.