Air Injection Vacuum Control Solenoid Valve: Testing and Inspection

Secondary air injection (AIR) solenoid valve -N112-, checking





Special tools and equipment
^ V.A.G 1526 A
^ V.A.G 1527 B
^ V.A.G 1594 A
^ V.A.G 1598/31
^ VAS 5051 with VAS 5051/1

Work sequence

Note: Secondary Air Injection (AIR) solenoid valve N112- and wiring are monitored by engine control module.

- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from list. Ignition must be on.
- Read out fault memory of engine control module.

If a malfunction relating to Secondary Air Injection (AIR) solenoid valve -N112 is displayed:





- Detach front engine cover (arrows -1- and -2-).
- Move lock carrier to service position





- Disconnect hoses from Secondary Air Injection (AIR) solenoid valve -N112- (arrow); leave connector attached.





- Connect test hose to valve connection marked with (arrow).

Vehicle diagnostic, testing and information system VAS 5051 connected up; vehicle self-diagnosis and vehicle system "01 Engine electronics" selected. Ignition must be on.





Indicated on VAS 5051:
- From list -1- select diagnostic function "03- Final control diagnosis".
- Keep touching 001, key, until the secondary air injection (AIR) solenoid valve -N112- is activated.
^ Valve must click...
^ ... and must open and close (can be checked by blowing into test hose).
- Terminate function "03- Final control diagnosis" by touching < key.
- Turn the ignition off.

If valve does not open or close properly:
- Replace secondary air inlet valve -N112.

If valve does not click in final control diagnosis:
Checking internal resistance
- Switch ignition off.





- Disconnect connector at secondary air injection (AIR) solenoid valve N112- (arrow).





- Connect multimeter to valve for resistance measurement.
^ Specification: 19 to 27 Ohms
If reading does not match specification:
- Replace secondary air injection (AIR) solenoid valve -N112-.
If reading matches specification:

Checking power supply
Requirements:
^ Fuse for secondary air inlet valve OK
Refer to Wiring Diagrams m.y 2003 >

^ Fuel pump relay OK

Note: Secondary Air Injection (AIR) solenoid valve N112- is supplied with power by way of the fuel pump relay.








- Connect voltage tester V.A.G 1527 B as follows.
- Briefly operate starter.
^ LED must light

If LED does not light:
- Use wiring diagram to check for open circuit in wiring from contact 1 of connector via fuse to fuel pump relay.
- Use wiring diagram to eliminate open circuit in wiring.

If LED lights:
Checking actuation
^ Vehicle diagnostic, testing and information system VAS 5051 connected up; vehicle self-diagnosis and vehicle system "01 Engine electronics" selected. Ignition must be on.





- Connect up voltage tester V.A.G. 1527 B between contacts 1 and 2.





Indicated on VAS 5051:
- From list -1- select diagnostic function "03 - Final control diagnosis".
- Keep touching > key, until the secondary air injection (AIR) solenoid valve -N112- is activated.
^ LED must flash
- Terminate function "03- Final control diagnosis" by touching < key.
- Switch ignition off.

If LED does not flash or if it is permanently lit:





- Connect up test box V.A.G 1598/31 to wiring harness connectors. Engine control module is not to be connected. Connect ground clip of test box to ground (not shown in Fig.).

CAUTION: So as not to destroy electronic components, select required measuring range before connecting test leads and observe test conditions.








- Check for open circuit and short to ground/positive in the following wiring.
- Use wiring diagram to eliminate open circuit in wiring/short circuit.