Testing secondary air inlet valve -N112 — AUDI

APG
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:

Connector / Contact · Measure against
1 · Engine earth

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
Motronic injection and ignition system

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

Connector / Contact · Test box V.A.G 1598/31 / Socket
2 · 105

Rectify any open/short circuit as necessary.

If the wiring is OK:

Install a new engine control unit: