With Manufacturer's Scan Tool

Mass Air Flow (MAF) Sensor -G70-, Checking

Special tools and equipment
- V.A.G1551 scan tool (or VAG1552 mobile scan tool) with VAGI551/3 cable
- VAG1598/31 test box
- Multimeter Fluke 83 or equivalent
- VAG1594 connector test kit
- Wiring diagram

Test requirements





- All fuses must be OK.
- Coolant temperature must be at least 80°C, See Display group 04, display field 3
- All electrical consumers like, for example, lights and rear window heating must be switched off.
- If vehicle is equipped with an A/C system, it must be switched off.
- For vehicles with automatic transmission, selector lever must be in -P-.

Test sequence
- Connect V.A.G 1551 scan tool (VAG1552). Start engine and select the Engine Control Module (ECM) using address word 01. Scan Tool Testing and Procedures

Indicated on display:

Rapid data transfer HELP
select function XX

- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.

Indicated on display:

Read measuring value block
Enter display group number XXX


- Press 0, 0 and 2 for the function "display group number 2", and then press Q to exit from input mode.

Indicated on display: (1 to 4 = display fields)

Read measuring value block 2 ->
1 2 3 4

- Check mass flow of air into engine in display field 4
Specification: 2.0 to 5.0 g/s

If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) sensor:
- Check voltage supply of Mass Air Flow (MAF) sensor.

If specified value is not obtained:
- Check signal and Ground (GND) wire of Mass Air Flow (MAF) sensor.

If specified value is obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.

Voltage supply for Mass Air Flow (MAF) sensor, checking





- Disconnect 5-pin connector -1- from Mass Air Flow (MAF) sensor -2-.
- Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.
- Start engine, and let run at idle.
Specification: 11 to 15 V

If there is no voltage:
- Switch ignition off.
- Check wire connection from terminal 2 to Fuel Pump (FP) relay -J17- according to wiring diagram.

If voltage supply and wires are OK:
- Switch ignition on.
- Connect multimeter to terminal 4 of connector and engine Ground (GND) for voltage measurement: Specification: 4.5 to 5.5 V

If there is no voltage:
- Switch ignition off.
- Check signal and ground wires.

Checking Signal and Ground Wires for Mass Air Flow (MAF) Sensor
- Remove wiper arms and wind cowl






- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.






- Check wires between test box and 5-pin connector for open circuits according to wiring diagram.
Terminal 5 + socket 29
Terminal 4 + socket 53
Terminal 3 + socket 27
Wire resistance: max: 1.5 Ohms

- Also check wires for short circuit to each other.
- Also check wires for shorts to battery B+ or Ground (GND).

If no DTCs are found in wires:
- Replace Mass Air Flow (MAF) sensor - G70-.
- Check DTC memory, repair any malfunctions and then erase DTC memory.
Reading Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes