Intake Change-Over -N156- & Tuning (IMT) Valve 2 -N261-

Intake Manifold Change-Over Valve - N156- And Intake Manifold Tuning (IMT) Valve 2 -N261-, Checking

- Run engine at idling speed for 2 or 3 minutes to build up vacuum pressure.
- Switch engine off.
- Switch ignition on.
- Perform output Diagnostic Test Mode (DTM) and activate intake manifold change-over valves.
Output Diagnostic Test Mode (DTM) (Function 03)

Indicated on display


Output DTM ->
Intake manifold change-over valve -N156-


Indicated on display


Output DTM ->
Intake manifold tuning valve 2 -N261-


Solenoid valves should click (clicking can be heard and felt). After 1 minute output DTM is terminated.

If one of the solenoid valves does not click:
- Switch ignition off.
- Unplug connector from relevant intake manifold change-over valve. If specification is attained, check voltage supply.







- Measure resistance between solenoid valve contacts using VAG 1526.
Specified value: 25...35 Ohms
- If specified value is not achieved, replace intake manifold change-over valve or IMT valve 2.
If specification is attained, check voltage supply.

Checking voltage supply of intake manifold change-over valve/IMT valve 2







- Connect diode test lamp VAG 1527 between engine Ground and socket 1 (positive) on connector using cables from adapter set VAG 1594.
- Operate starter briefly.
Diode test lamp should illuminate.

If the diode test lamp does not illuminate:

- Check fuse for intake manifold change-over valve/IMT valve 2.

If the fuse is OK:

- Check for open circuit and short in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change-over valve/IMT valve 2.

If the voltage supply is OK, check actuation.
- Re-insert fuel pump relay and fuse.

Checking actuation of intake manifold change-over valve/IMT valve 2

- Connect diode test lamp VAG 1527 between sockets 1 and 2 on connector for intake manifold change-over valve/IMT valve 2 using cables from adapter set VAG 1594.
- Perform output DTM and actuate intake manifold change-over valve or IMT valve 2.
Output Diagnostic Test Mode (DTM) (Function 03)

Indicated on display


Output DTM ->
Intake manifold change-over valve -N156-


Indicated on display


Output DTM ->
Intake manifold tuning valve 2 -N261-


If the diode test lamp does not flash or is continuously lit:

- Check wiring.

Checking wiring
- Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module.
Connecting VAG 1598/31 Test Box
- Check following wiring connections for open circuit and short circuit to positive or Ground.

Connector for intake manifold
change-over valve socket Test box VAG 1598/31 socket

2 48

Connector for intake manifold
tuning valve 2 socket Test box VAG 1598/31 socket

2 45

Wire resistance: max. 1.5 Ohm

- If wiring is OK replace engine control module.
- Check intake manifold change-over again for function.
- Read readiness code. Generate readiness code again if DTC memory was erased.
Readiness Code, Generating