Audi Workshop Service and Repair Manuals

Checking intake manifold pressure sender -G71-

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-

Procedure   Note t  The intake manifold pressure sender -G71- and the wiring connections are monitored by the engine control unit. t  Fitting location of intake manifold pressure sender -G71--arrow-: in charge air cooler at front left of engine compartment. 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 intake manifold pressure sender -G71- is displayed: –  Press ← key to terminate function “Interrogate fault memory”.

Checking operation: –  Leave engine running at idling speed. Display on -VAS 5051B-: –  From menu -1-, select diagnosis function “Measured values” and press → key to continue.

Display on -VAS 5051B-: –  Press keys 11 on keypad -1- to select “Display group 011” and confirm entry by pressing Q key.

Display on -VAS 5051B-: –  Check display in display zones -2- and -3-. l  Specification: The pressures should be the same (tolerance: ± 100 mbar). –  Check other possible causes for reading not matching specification: Charge pressure too low: –  Check charge pressure control: vehicles with plug in intake manifold → Chapter, vehicles without plug in intake manifold → Chapter. Charge pressure too high: –  Check charge pressure control solenoid valve -N75- → Chapter. –  Check whether hose for charge pressure control has become detached or clogged. –  Check linkage and vacuum unit for charge pressure control → Chapter. If no fault is found: –  Check wiring.

Checking wiring 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.

–  Unplug electrical connector -arrow- at intake manifold pressure sender -G71-.

–  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	3/16	52
3	3/14	31
4	3/15	71

–  Repair wiring connection if necessary. If no fault is found: –  Renew intake manifold pressure sender -G71-.