Checking function

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2001 Volkswagen Jetta, 2001 Volkswagen Golf, 2000 Volkswagen Jetta, 2000 Volkswagen Golf, and 1999 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.

Start engine and run at idling speed.
Switch ignition off.
Observe position of lever on intake manifold flap change-over valve (2nd technician required).

The intake manifold flap must (after ignition is switched off) close and after approx. 3 seconds open again.

If change-over does not occur, perform the following checks:

Fig 1: V.A.G 1390 Connected To Vacuum Unit

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Pull vacuum hose off vacuum unit - 1 -.
Connect hand vacuum pump V.A.G 1390 or equivalent to vacuum unit.
Operate hand vacuum pump and check intake manifold flap change-over mechanism for ease of movement and operation.
Check vacuum lines for correct connection.

If no malfunction is found in the mechanical components:

Check intake manifold flap change-over valve.