Vacuum System, Checking For Leaks

- Let engine run 2 to 3 minutes at idle (for vacuum to build up).
- Switch ignition off.
- Remove 2-pin connector from intake manifold tuning valve -N156- (change-over valve).







- Connect jumper wire (from VAG 1594) from one terminal of -N156- to engine ground.
- Use VAG 1248/3A remote, adapter wire VAG 1348/3-2 and auxiliary wire to connect second terminal of -N156- to B+.
- Activate intake manifold tuning valve -N156-, using remote control VAG 1348/3A, for approx. 2 to 3 min.
- The vacuum solenoid must remain actuated during this time.

If vacuum solenoid releases, check solenoid as follows:
- Remove vacuum line from vacuum solenoid for intake manifold change-over.
- Connect VAG 1390 hand pump to vacuum solenoid.
- Activate VAG 1390 hand pump and watch change-over process.
- Check vacuum solenoid for leaks.
- Vacuum solenoid should not return to initial position as long as vacuum is being applied by hand pump.

If vacuum solenoid returns:
- Replace vacuum solenoid.