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- or -V.A.G 1526 B-

t	Voltage tester -V.A.G 1527 B-

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

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

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

Procedure l  Vehicle diagnostic, testing and information system -VAS 5051- is connected; vehicle self-diagnosis and vehicle system “01 - Engine electronics” is selected. When doing this, the ignition must be switched on. l  Fault memory of engine control unit interrogated.   Note The secondary air inlet valve -N112- and the wiring connections are monitored by the engine control unit. If a fault relating to secondary air inlet valve -N112- is displayed:

–  Unbolt coolant expansion tank -2--arrows-. –  Unplug electrical wire for coolant shortage indicator switch -F66- at bottom of expansion tank and move expansion tank to one side with coolant hoses -1- and -3- attached.

–  Disconnect hoses -1- and -2- from secondary air inlet valve; leave electrical connector -3- attached.

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

Display on -VAS 5051- –  From the menu -1- select the diagnostic function “03 - Final control diagnosis”. –  Press the → button several times until the secondary air inlet valve -N112- is activated. l  The valve should click and open and close (check by blowing into the test hose). –  Exit function “03 - Final control diagnosis” by pressing the ← key, and switch off the 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 electrical connector -3- at secondary air inlet valve -N112-.

–  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 the specification is obtained:

Checking voltage supply l  Fuse for secondary air inlet valve OK. l  Fuel pump relay -J17- 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- between contact -1- and 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 (refer to current flow diagram). If the LED lights up:

Checking activation –  Connect voltage tester -V.A.G 1527 B- between contacts -1- and -2-. –  Repeat function “03 - Final control diagnosis”. –  Press the → button several times until the secondary air inlet valve -N112- is activated. l  The LED should flash. –  Exit function “03 - Final control diagnosis” by pressing the ← key, and switch off the ignition. If the LED does not flash: –  Connect adapter cable -V.A.G 1598/31- (test box) to wiring harness for engine control unit, but do not connect the engine control unit itself → Rep. Gr.24.

–  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-	71

–  Repair wiring connection if necessary. If no fault in wire is detected: –  Renew engine control unit.