Boost Solenoid: Testing and Inspection

Boost Pressure System, Checking





Special tools, workshop equipment, test and measuring appliances and auxiliary items required
^ VAG 1390 Hand vacuum pump
^ Fluke 83 Multimeter or equivalent
^ VW 1594 Adaptor kit
^ VAG 1598/22 Test Box
^ VAG 1551/1552 Scan Tool using
VAG 1551/3 Adaptor cable
^ Wiring diagram

Checking requirements
^ No intake or exhaust system leaks.
^ No malfunctions in engine and fuel injection system, e.g. start of injection, injectors and compression pressure.
^ Engine oil temperature min. 80°C minimum.

Test sequence
Observe following if test and measuring instruments are required during a test drive:
^ Test and measuring instruments must be secured to rear seat and operated by a 2nd person from this location.

WARNING: If test and measuring instruments are operated from the front passenger's seat and the vehicle is involved in an accident, there is the possibility that the person sitting in this seat could receive serious injuries from the test instruments if the airbag is triggered.

- Boost pressure is measured using the VAG 1551/1552 Scan Tool during a test drive.
- Connect VAG 1551/1552 Scan Tool
^ Engine must be running at idle
- Press 0 and 1 buttons to select address word 01 "Engine electronics"





Display will appear as shown

- Press 0 and 8 buttons to select Function 08 "Read measuring value block"
- Press 0 button to enter input





Display will appear as shown
- Press, 0, 1 and 1 buttons to select Display Group 11
- Press Q button to enter input





- Display will appear as shown
- Accelerate vehicle in 3rd gear (manual transmission) or with driving range 2 selected (automatic; transmission) from about 1500 rpm using Wide Open Throttle.
- Press VAG 1551 PRINT button at approx. 3000 rpm.





Specification in display zone 3: 1700 to 2300 mbar
If specification not obtained
- With vehicle stationary perform Output Diagnostic Test Mode to activate the Wastegate Bypass Regulator valve





Display will appear as shown

Notes:
^ The Wastegate Bypass Regulator valve must function and the Boost pressure control valve rod must move to and fro (at least 3 to 4 times, as long as there is vacuum in the reservoir).
^ Due to rod location, movement can only be observed by using a mirror.

- Perform Output Diagnostic Test Mode
If rod moves and boost pressure specifications not obtained during test drive
- Replace turbocharger.
If rod does not move because Wastegate Bypass Regulator valve not working:
- Check Wastegate Bypass Regulator valve N75
- Check vacuum hoses
If rod does not move but solenoid operates





- Connect VAG 1390 hand vacuum pump to Wastegate Bypass Regulator valve and verify that rod moves freely.
If rod does not move easily
- Replace turbocharger assembly