A6 Quattro Wagon V6-2.8L (AFC) (1995)
Mass Air Flow Sensor: Testing and Inspection
NOTE:
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For functional testing of the Mass Air Flow sensor, also see On-Board Diagnostics, "Basic Setting" function 04. See: Computers and Control
Systems/Testing and Inspection
TEST CONDITION
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Circuit breaker in yellow fuse holder - OK (In electronics box, passenger side footwell)
CHECKING POSITIVE BATTERY VOLTAGE (B+) SUPPLY.
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Ignition switched OFF
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Disconnect harness connector from Mass Air Flow (MAF) sensor.
CAUTION:
Wait 30 seconds after switching OFF the ignition BEFORE disconnecting the Engine Control Module (ECM) harness connector.
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Connect multimeter (Fluke 83 or equivalent) between connector terminals 2 and 3 using adapter cables from VW 1594 connector test kit.
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Switch ignition ON.
Specified value: approx. 12-14 volts.
If specified value is not obtained:
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Check Circuit breaker in yellow fuse holder (In electronics box, passenger side footwell).
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Check continuity between connector terminal 3 and circuit breaker according to wiring diagram.
Specified value: maximum 0.5 ohms
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Check continuity between terminal 2 and Ground (GND).
Specified value: maximum 0.5 ohms
Check wiring between ECM and MAF sensor
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Connect VAG 1598 test box with VAG 1598/11 adapter harness to engine wiring harness. Refer to VAG 1598 Pin Out Box Connecting. See:
Computers and Control Systems/Testing and Inspection/Scan Tool Testing and Procedures/Scan Tool Testing/Scan Tool Connecting and
Initial Checks/Connecting and Testing VAG 1598 Pin Out Box
Adapter harness for ECM is not connected.
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Check signal wire for continuity between MAF sensor terminal 1 and test box socket 42.
Specified value: maximum 1.0 ohm
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Check ground wire for continuity between MAF sensor connector terminal 2 and test box socket 45.
Specified value: maximum 1.0 ohm
If specified values are not obtained:
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Find and eliminate open or short circuit in wiring between MAF sensor connector and ECM connector A.
MAF sensor
ECM connector A
connector
1
2
2
5
NOTE:
Use only gold-plated terminals when replacing mass air flow sensor connector terminals.
Checking function of MAF sensor
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Push back protective boot on MAF sensor connector (leaving sensor connected).
NOTE:
The connector terminals are appropriately identified on the back of the connector:
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Connect multimeter (Fluke 83 or equivalent) between connector terminals 1 and 2, using adapter cables from VW 1594 connector test kit.
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Switch ignition ON.
Specified value: 0.3-1.1 volts
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Let engine run, switch all electrical consumers off (radiator cooling fan must not run) and vary engine speed continuously between idle and
4000 RPM.
Specified value: voltage must vary between 1.5 to maximum 3.4 volts, corresponding to engine speed.
If specified values are not obtained:
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Replace mass air flow sensor.