Combination Valve for Secondary Air Injection (AIR), checking function and proper seal

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2001 Volkswagen Jetta, 2000 Volkswagen Jetta, 2000 Volkswagen Golf, 2000 Volkswagen GTI, and 1999 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.

The following procedure is used to test all combination valves.

Special tools, testers and auxiliary items required

Hand vacuum pump.

Test conditions

Vacuum lines and hose connections free of leaks.
Vacuum lines not plugged.

Test sequence

Remove the vacuum hose from the combination valve.

Fig 1: Hand Vacuum Pump V.A.G 1390 Connected To Combination Valve Vacuum Connection

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect hand vacuum pump V.A.G 1390 to combination valve vacuum connection.

Fig 2: Identifying Air Duct Hose

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove the air duct hose - arrow - from the Throttle Valve Control Module J338 and position aside.

Fig 3: Identifying Secondary Air Injection Hose

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect the Secondary Air Injection hose - arrow -.
Inject a light air pressure into the in Secondary Air Injection hose to close the combination valve. (do not use compressed air).

The combination valve should close and seal. Air should not be able to pass through the combination valve.

Operate the hand vacuum pump.

The combination valve should open. Air should be able to pass through the combination valve.

If combination valve does not open:

Replace the faulty combination valve. Refer to 26 EXHAUST SYSTEM, EMISSION CONTROLS .

End of procedure