Audi Workshop Service and Repair Manuals

Checking exhaust gas recirculation valve -N18-

Special tools and workshop equipment required

t	Hand-held multimeter -V.A.G 1526D-

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

t	Adapter -V.A.G 1598/30- (engine code AFB for vehicles with manual gearbox or automatic gearbox; engine code AKN for vehicles with manual gearbox)

t	Adapter cable, 121-pin -V.A.G 1598/31- (engine code AKN for vehicles with automatic gearbox)

t	Vehicle diagnostic, testing and information system -VAS 5051B-

t	Hand vacuum pump -VAS 6213-

Procedure   Note The exhaust gas recirculation valve -N18- and the wiring connections are monitored by the engine control unit. l  Vehicle diagnostic, testing and information system -VAS 5051B- connected. l  Engine running. l  Vehicle self-diagnosis and vehicle system “01 - Engine electronics” selected.

Display on -VAS 5051B-: –  From menu -1-, select diagnostic function “Interrogate fault memory” and press → key to continue. If a fault relating to exhaust gas recirculation valve -N18- is displayed: –  Press ← key to terminate function “Interrogate fault memory”.

Checking mechanical operation –  Switch off ignition. –  Unplug electrical connector at exhaust gas recirculation valve -N18-. –  Detach hose at vacuum connection -3- (leave hose at connection -2- attached to mechanical exhaust gas recirculation valve). –  Connect hand vacuum pump -VAS 6213- to vacuum connection -3-.

–  Use a test lead from auxiliary measuring set -V.A.G 1594C- to connect contact -2- of solenoid valve to battery positive “+”. –  Connect contact -1- to earth. l  The valve should click.

–  Detach caps on engine cover panel. –  Unbolt and remove engine cover panel -arrows-.

–  Disconnect vacuum hose from mechanical exhaust gas recirculation valve -arrow-. –  Operate hand vacuum pump -VAS 6213-. l  Vacuum is applied to disconnected vacuum hose (feel with finger).

–  Detach earth connection from contact -1- of solenoid valve. –  Operate hand vacuum pump -VAS 6213-. l  Vacuum is not applied to disconnected vacuum hose (feel with finger). If the specifications are not obtained: –  Renew exhaust gas recirculation valve -N18-.

Checking voltage supply –  Connect up multimeter -V.A.G 1526D- for voltage measurement as follows:

Connector Contact	Measure against
2	Earth

–  Switch on ignition. l  Specification: approx. battery voltage. If specification is not obtained: –  Check wiring connection for open circuit and short to positive or earth → Current flow diagrams, Electrical fault finding and Fitting locations.

Checking internal resistance –  Unplug electrical connector at exhaust gas recirculation valve -N18-. –  Connect multimeter (resistance measuring range) to valve. l  Specification: 14 ... 20 Ω. If specification is not obtained: –  Renew exhaust gas recirculation valve -N18-.

Checking signal wire –  If fitted, remove seal from plenum chamber cover -arrows-. –  Detach plenum chamber cover -1- towards the front.

–  Remove cover for electronics box in plenum chamber -arrows-.

–  Carefully prise off retaining strap -arrow- using a screwdriver. –  Release retaining clip and unplug connectors from control unit.

Engine code AFB for vehicles with manual gearbox or automatic gearbox, engine code AKN for vehicles with manual gearbox: –  Connect adapter -V.A.G 1598/30- to unplugged connectors for engine control unit (not to control unit).

Engine code AKN for vehicles with automatic gearbox: –  Connect adapter cable, 121-pin -V.A.G 1598/31- to connector of wiring harness (do not connect engine control unit). –  Connect earth clip of adapter cable to earth (not shown in illustration). All vehicles (continued):   Caution Electronic components are susceptible to damage. Select the appropriate measuring range before connecting the test leads and observe test requirements.

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

Connector Contact	-V.A.G 1598/30- Socket	-V.A.G 1598/31- Socket
1	2/13	61

–  Rectify any open/short circuit as necessary.