Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ 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

Test requirement:

• ● Connect vehicle diagnosis, testing and information system VAS 5051, select "Vehicle self-diagnosis" and vehicle system "01 - Engine electronics".

Test sequence

Note:

Secondary air inlet valve -N112 and associated wiring are monitored by engine control unit.

• ‒ Interrogate fault memory of engine control unit.

If the display shows a fault relating to secondary air inlet valve -N112:

• ‒ → Disconnect secondary air inlet valve -N112 -arrow- from bracket.
• ‒ Disconnect hoses from secondary air inlet valve; electrical connector remains connected.

• ‒ → Connect test hose to connection on valve indicated by arrow.

→ Display on VAS 5051:

• ‒ Select diagnosis function "03 - Final control diagnosis" from the menu -1-
• ‒ Activate secondary air inlet valve -N112:

• ◆ The valve should click...
• ◆ ...and open and close (can be checked by blowing into test hose).

If the valve does not open and close properly:

• ‒ Renew secondary air inlet valve -N112.

If valve does not click during final control diagnosis:

Testing internal resistance

• ‒ Switch off ignition.
• ‒ → Unplug connector from secondary air inlet valve -N112 -arrow-.

• ‒ → Connect multimeter between contacts 1 and 2 of valve (resistance measurement range).
• ‒ Specification: 52.5 ... 62.5 ωat room temperature

If the specification is not attained:

• ‒ Renew secondary air inlet valve -N112.

If the specification is obtained:

Checking voltage supply

Requirements for test:

• ● Fuse for secondary air inlet valve OK.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ● Fuel pump relay OK

Note:

The secondary air inlet valve -N112 receives its power supply via the fuel pump relay.

• ‒ → Connect voltage tester V.A.G 1527 B as follows:

• ‒ Operate starter briefly.
• ‒ The LED should light up.

If the LED does not light up:

• ‒ Test for open circuit in wiring connection between fuel pump relay and contact 1 on connector via fuse:

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ Rectify any open circuits.

If the LED lights up:

Checking activation

• ‒ → Connect voltage tester V.A.G 1527 B to contact 1 (positive) and contact 2 of the connector.

→ Display on VAS 5051:

• ‒ Select diagnosis function "03 - Final control diagnosis" from the menu -1-
• ‒ Activate secondary air inlet valve -N112:
• ‒ The LED should flash slowly.

If the LED lamp does not flash or if it lights up continuously:

• ‒ → Connect test box V.A.G 1598/31 to wiring harness connectors. The engine control unit itself does not need to be connected to the test box. Connect earth clamp on test box to earth -arrow-.

=> Motronic injection and ignition system; Repair group 24

• ‒ Test for open circuit and short to positive or earth in the following wiring connection:

• ‒ Rectify any open/short circuit as necessary.

If the wiring is OK:

• ‒ Install a new engine control unit: