Air Flow Meter/Sensor: Testing and Inspection

Mass Air Flow (MAF) Sensor, Checking

Special tools and equipment required
- Scan tool VAG 1551 or vehicle system tester VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Check conditions







- Fuse 43 must be OK.
- Coolant temperature must be at least 80 °C, See display group 04, display zone 3.
- All electrical consumers, e.g. lights and rear window heating must be switched off
- If the vehicle is equipped with an air conditioner, this must be switched off.
- On vehicles with automatic transmission selector lever in "P" or "N" position

Test sequence
- Connect scan tool VAG 1551 (VAG 1552). Start engine and select "Address word" 01 of engine control module. When doing this the engine must be running at idling speed.
(Connecting scan tool and selecting engine control module). Refer to "VAG 1551 Scan Tool" [1][2][3][4][5]Connecting VAG 1551 Scan Tool

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Indicated on display:


Read measured value block HELP
Input display group number XXX


- Press keys 0, 0 and 2 for "Display group number 2" and confirm entry with Q key.

Indicated on display: (1-4 = Display zones)


Read measured value block 2 ->
1 2 3 4


- Check the air mass drawn in in display zone 4

Specification: 2.0 - 4.5 g/s

If the specification is obtained but there is a malfunction regarding the Mass Air Flow (MAF) sensor registered in the Diagnostic Trouble Code (DTC) memory:
- Check the voltage supply for the Mass Air Flow (MAF) sensor.

If the specification is not obtained:
- Check the signal and Ground wires for the Mass Air Flow (MAF) sensor.

If the specification is obtained:
- Press the -> key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.

Checking Voltage Supply For Mass Air Flow (MAF) Sensor







- Pull 5 pin connector -1- off Mass Air Flow (MAF) sensor -2-.
- Connect multimeter to measure voltage on connector contact 2 and engine Ground.
- Start engine and run at idling speed.
Specification: 11 - 15 V


If no voltage is present:
- Switch off ignition.
- Check wiring from contact 2 to fuel pump relay (J17) according to wiring diagram.


If the voltage supply and wiring is OK:
- Switch ignition on.
- Connect multimeter to measure voltage on connector contact 4 and engine Ground:
Specification: 4.5 - 5.5 V


If no voltage is present:
- Switch off ignition.
- Check the signal and Ground wires.

Testing signal and Ground wires for Mass Air Flow (MAF) sensor







- Connect test box VAG 1598/31 to control module wiring harness. The engine control module remains disconnected.







- Check wiring for open circuit between test box and 5-pin connector using wiring diagram.
Contact 5 + socket 29
Contact 4 + socket 53
Contact 3 + socket 27
Wire resistance: Max. 1.5 ohms

- Additionally check wires for short to one another.
- Additionally check the wiring for short to battery positive or Ground.

If no wiring fault is detected:
- Replace Mass Air Flow (MAF) sensor (G70) item 2. Service and Repair