Intake Air Switch-Over Valve -N335- Checking

Intake Air Switch-over valve -N335- Checking

In all S6 models a flap is switched in the air filter via the intake air switch-over valve - N335-.

Only perform test when there is a lack in performance or a DTC was registered.

The change-over on a shorter intake path in the air filter is dependent on speed and load.







NOTE: At the front of the air filter lower housing there is a round opening. When reaching inside with one finger a flap can be felt.

Checking function

- Start engine.
- Accelerate sharply
Flap in lower part of air filter must open at same time.

If the flap does not open when accelerating sharply:

- Check intake air switch-over valve -N335-.
- Check vacuum system for leaks. Vacuum System, Checking

Checking intake air switch-over valve -N335-

- Switch ignition on.
- Perform output Diagnostic Test Mode (DTM) and actuate intake air switch-over valve -N335. Output Diagnostic Test Mode (DTM) (Function 03)

Indicated on display


Output Diagnostic Test Mode ->
Intake air switch-over valve -N335-


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

If the solenoid valve does not click:

- Switch ignition off.
- Unplug connector from intake air switch-over valve -N335-.







- Measure resistance between contacts on solenoid valve using handheld multimeter VAG 1526.
Specified value: 25...35 Ohms

If the specified value is not attained:
- Replace intake air switch-over valve -N335-.

If the specified value is attained:
- Check voltage supply.

Checking voltage supply to intake air switch-over valve -N335-







- 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 diode test lamp does not illuminate:
- Check fuse for intake air switch-over valve -N335-.

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 air switch-over valve -N335-.

If the voltage supply is okay:
- Check actuation of intake air switch-over valve - N335-.
- Re-insert fuel pump relay and fuse.

Checking actuation of intake air changeover valve -N335

- Connect diode test lamp VAG 1527 between sockets 1 and 2 on connector for intake air switch-over valve -N335- using cables from adapter set VAG 1594.
- Perform output Diagnostic Test Mode (DTM) and actuate intake air switch-over valve -N335-. Output Diagnostic Test Mode (DTM) (Function 03)

Indicated on display


Output Diagnostic Test Mode ->
Intake air switch-over valve -N335-


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 the following wiring connections for open circuit and short circuit to positive or Ground.

Unplug connector from intake air
switchover valve -N335- 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 switch-over valve again for function.
- Read readiness code. Generate readiness code again if DTC memory was erased. Readiness Code, Generating