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 C- or -V.A.G 1526 A-

t	Voltage tester -V.A.G 1527 B-

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

t	Adapter cable -V.A.G 1598/31- (test box)

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

Procedure   Note The secondary air inlet valve -N112- and the wiring connections are monitored by the engine control unit. –  Open rear ashtray and remove cover for diagnostic connector.

–  Connect up vehicle diagnostic, testing and information system -VAS 5051- with diagnosis lead -VAS 5051/1-, press vehicle self-diagnosis button and select vehicle system “01 - Engine electronics”. When doing this, the engine must be running at idling speed.

Display on -VAS 5051-: –  From list -1-, select diagnosis function “02 - Interrogate fault memory”. If a fault relating to secondary air inlet valve -N112- is displayed: –  Terminate function “02 - Interrogate fault memory” by touching ← key. –  Press function “06 - End output” and switch off ignition.

–  Unfasten screw connections -arrows- and detach engine cover panels -A ... C-.

–  Unscrew hose connections and bolt connections on the air duct at the points indicated by -arrows- and remove the air duct.

–  Unplug electrical connectors -1- and -2-. –  Unscrew nuts -arrows- and remove control units for exhaust gas temperature sender. –  Disconnect bracket for secondary air inlet valve -N112- from intake manifold; leave electrical connector attached. –  Detach hoses from secondary air inlet valve -N112-.

–  Connect test hose to secondary air inlet valve -N112- connector marked with an -arrow-.

–  Switch on ignition and select vehicle system “01 - Engine electronics”. Display on -VAS 5051-: –  From the menu -1- select the diagnostic function “03 - Final control diagnosis”.

–  Press the → key repeatedly until the following display appears: Display on -VAS 5051-: 2 -  Secondary air inlet valve -N112- A -  Actuator is running; continued switching is allowed l  The valve should click and open and close (check by blowing into the test hose). –  Press the ← key to exit from function “03 - Final control diagnosis”. –  Press function “06 - End output” and switch off ignition. If valve clicks but does not open or close correctly: –  Renew secondary air inlet valve -N112-. If valve does not click:

Checking internal resistance –  Detach electrical connector at secondary air inlet valve -N112-. –  Connect hand-held multimeter -V.A.G 1526 C- to measure resistance between contacts on secondary air inlet valve -N112-. 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 -N112- OK → Current flow diagrams, Electrical fault finding and Fitting locations. l  Fuel pump relay -J17- OK → Current flow diagrams, Electrical fault finding and Fitting locations.   Note The secondary air inlet valve -N112- is supplied with power via the fuel pump relay -J17-.

–  Connect voltage tester -V.A.G 1527 B- between contact -1- of connector for secondary air inlet valve -N112- and engine earth. –  Operate the starter briefly. l  The LED should light up. If LED does not light up: –  Repair wiring from contact -1- of connector, via fuse, to fuel pump relay -J17- (refer to current flow diagram). If the LED lights up:

Checking activation –  Connect voltage tester -V.A.G 1527 B- between contact -1- and -2- of connector for secondary air inlet valve -N112-. –  Switch on ignition and select vehicle system “01 - Engine electronics”.

–  Repeat function “03 - Final control diagnosis”. –  Press the → key repeatedly until the following display appears: Display on -VAS 5051-: 2 -  Secondary air inlet valve -N112- A -  Actuator is running; continued switching is allowed l  The LED should flash. –  Press the ← key to exit from function “03 - Final control diagnosis”. –  Press function “06 - End output”. –  Switch off ignition and unplug diagnostic connector.

If the LED does not flash: –  Connect adapter cable -V.A.G 1598/31- (test box) to connectors of wiring harness; do not connect engine control unit. Connect earth clip of test box to earth (not shown in illustration).   Caution To prevent damage to electronic components, select appropriate measuring range before connecting measuring leads and observe test requirements.

–  Check for open circuit and short to positive or earth in the following wiring:

Connector Contact	Adapter cable -V.A.G 1598/31- (test box) Socket
-2-	44

–  Repair wiring connection if necessary.