Mass Air Flow Sensor, Checking: Notes

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Mass Air Flow (MAF) Sensor - G70- fuse OK.
  Fig 1: Identifying Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of AUDI OF AMERICA, LLC
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Coolant Temperature at least 80° C.
• Ignition switched off.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis 

-- Connect the scan tool.

-- Start engine and let it run at idle.

-- Using the scan tool, Check the air flow quantity of the Mass Air Flow (MAF) Sensor -G70- at idle:

Diagnostic text		Specified value
Air flow quantity at Mass Air Flow (MAF) sensor
Engine warmed up, running at idle		2.00 to 5.00 g/sec

-- Switch the ignition off.

If the specified value was obtained:

If DTC Memory has a DTC concerning Mass Air Flow (MAF) Sensor - G70 - Fault may be intermittent.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

-- Go to Final procedures

If the specified value was Not obtained:

-- Disconnect the Mass Air Flow (MAF) Sensor - G70 - electrical harness connector.

-- Turn the ignition switch ON.

-- Using a Multimeter, connect the red Multimeter lead to terminal 3 of the Mass Air Flow (MAF) Sensor - G70 - module connector and the black lead to ground.

Specified value: Battery voltage.

-- Switch the ignition off.

If the specified value was Not obtained:

-- Check for an open or short to ground in circuit between terminal 3 and fuse SC 1 in Fuse Panel C.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- Repair the circuit and replace any open fuses.

-- Go to Final procedures

If the specified value was obtained:

-- Connect the black Multimeter lead to terminal 2 of the Mass Air Flow (MAF) Sensor - G70 - harness connector and the red lead to Battery voltage.

-- Turn the ignition switch ON.

Specified value: Battery voltage.

-- Switch the ignition off.

Continue test according to the following table:

Value	Cause	Test
If the specified value was not obtained:	Open or shorted circuit	CHECKING WIRING
If the specified value was obtained:	Check reference signal circuit	CHECKING WIRING