Audi Workshop Service and Repair Manuals

Checking secondary air inlet valve -N112-

Special tools and workshop equipment required

t	Hand-held multimeter -V.A.G 1526 A-

t	Voltage tester -V.A.G 1527 B-

t	Auxiliary measuring set -V.A.G 1594 A-

t	Test box -V.A.G 1598/31-

t	Vehicle diagnosis, testing and information system -VAS 5051-

Test sequence l  Vehicle diagnostic, testing and information system -VAS 5051- is connected; vehicle self-diagnosis and vehicle system “01 - Engine electronics” is selected.   Note The secondary air inlet valve -N112- and the wiring connections are monitored by the engine control unit. –  Read out fault memory of engine control unit. If a fault relating to secondary air inlet valve -N112- is displayed:

–  Remove engine cover panel -arrows-.

–  Disconnect hoses from secondary air inlet valve -N112--arrow-; leave electrical connector attached.

–  Connect test hose to the valve connector marked with an -arrow-.

Display on -VAS 5051-: –  From menu -1- select diagnosis function “03 - Final control diagnosis”. –  Press the → button until the secondary air inlet valve -N112- is actuated. l  The valve should click and open and close (check by blowing into the test hose). –  Switch off ignition. If valve does not open or close correctly: –  Renew secondary air inlet valve -N112-. If valve does not click during final control diagnosis:

Checking internal resistance –  Unplug connector from secondary air inlet valve -N112--arrow-.

–  Connect multimeter (resistance measuring range) to valve. l  Specification: 25 ... 35 Ω. If the specification is not attained: –  Renew secondary air inlet valve -N112-. If specification is obtained: Checking voltage supply l  Fuse for secondary air inlet valve OK. → Current flow diagrams, Electrical fault finding and Fitting locations l  Fuel pump relay OK.   Note The secondary air inlet valve -N112- is supplied with power via the fuel pump relay.

–  Connect voltage tester -V.A.G 1527 B- as follows:

Connector contact	Measure against
-1-	Engine earth

–  Operate the starter briefly. l  The LED should light up. –  Switch off ignition. If LED does not light up: –  Check for open circuit in wiring from contact -1- of connector via fuse to fuel pump relay → Current flow diagrams, Electrical fault finding and Fitting locations. –  If necessary repair wiring connection. If the LED lights up:

Checking activation –  Connect voltage tester -V.A.G 1527 B- to contacts -1- (plus) and -2- of the connector.

Display on -VAS 5051-: –  From menu -1- select diagnosis function “03 - Final control diagnosis”. –  Press the → button until the secondary air inlet valve -N112- is actuated. l  The LED should flash. –  Switch off ignition.

If the LED does not flash or lights up continuously: –  Connect test box -V.A.G 1598/31- to connectors of wiring harness; do not connect engine control unit. Connect earth clamp of test box to earth (not shown in illustration) → Motronic injection and ignition system (6-cyl.); Rep. Gr.24. –  Check for open circuit and short to positive or earth in the following wiring:

Connector contact	Test box -V.A.G 1598/31- Socket
2	44

–  If necessary repair wiring connection.