Engine code ALH

WARNING: This page is about a different variant/trim than selected.

Test conditions

No malfunctions in DTC memory. Refer to 01 ON BOARD DIAGNOSTIC (OBD) from M.Y. 99-01 or 01 ON BOARD DIAGNOSTIC (OBD) from M.Y. 2002 and on
No leaks on intake or exhaust side.
No malfunctions in engine/injection system including start of injection, injector nozzles, compression pressure.
Engine oil temperature at least 80 ° C

Test sequence

Observe the 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.

If test and measuring instruments are operated from the front passengers seat and the vehicle is involved in an accident, there is a possibility that the person sitting in this seat may receive serious injuries when the airbag is triggered.

Connect scan tool V.A.G 1551 or mobile scan tool V.A.G 1552 with cable V.A.G 1551/3 and select control module for engine electronics with the "address word" 01. Engine must run at idle during this: Refer to 01 ON BOARD DIAGNOSTIC (OBD) from M.Y. 99-01 or 01 ON BOARD DIAGNOSTIC (OBD) from M.Y. 2002 and on

Scan tool display:

Quick data transfer HELP
Select function XX

Press buttons 0 and 8 for the function "Reading measuring value blocks" and press Q button to confirm input.

Scan tool display:

Read measuring value block HELP
Enter display group number XXX

Press buttons 1 0 and 1 for the "Display group number 11" and press Q button to confirm input.
Scan tool display:

Read measuring value block 11
840/min 938 mbar 978 mbar 92%

Accelerate vehicle in 3rd gear at full throttle from approx. 1500 RPM.
When at 3000 RPM, press the PRINT button on scan tool V.A.G 1551 or mobile scan tool V.A.G 1552.

Specified value on scan tool V.A.G 1551 or mobile scan tool V.A.G 1552 : 1700 to 2250 mbar (in display field 3)

Read measuring value block 11 ->
3090/min 1866 mbar 1917 mbar 62 %

If specification is not obtained:

Perform output diagnostic test and activate Wastegate Bypass Regulator Valve: Refer to 01 ON BOARD DIAGNOSTIC (OBD) from M.Y. 99-01 or 01 ON BOARD DIAGNOSTIC (OBD) from M.Y. 2002 and on

Scan tool display:

Output diagnostic test ->
Wastegate Bypass Regulator Valve N75

The valve must work and thereby it must move the rod of the vacuum diaphragm for boost pressure regulation on the turbocharger back and forth (at least 3 to 4 times, as long as vacuum is available in the vacuum reservoir).

If the rod moves and the boost pressure values are not achieved, replace turbocharger.

If the rod does not move because the valve is not working:

Check Wastegate Bypass Regulator Valve N75.
Check vacuum hoses. Refer to Turbocharger line connections .

If the rod does not move although the valve is working:

Fig 1: Identifying Hand Vacuum Pump V.A.G 1390 Connected To Boost Pressure Regulator Valve

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Connect hand vacuum pump V.A.G 1390 to boost pressure regulator valve and check the free movement of the rod.
If the rod does not move freely, replace turbocharger.