Air Flow Meter/Sensor: Testing and Inspection

Mass Air Flow (MAF) sensor, checking

Special tools and equipment
- V.A.G 1551 scan tool (or VAG 1552 mobile scan tool) with VAG 1551/3B cable
- VAG 1598/31 adapter cable
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram

Test requirements







- Fuse no. 34 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- or -N-.

Test sequence
- Connect V.A.G 1551 scan tool (VAG 1552). Start engine and select the Engine Control Module (ECM) using address word 01. (connecting scan tool and selecting ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551 Scan Tool", Testing and Inspection

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 HELP
Enter display group number XXX


- Press buttons -0-, -0- and -2- to select "Display group number 2". Press -Q- button to confirm input.

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 4.5 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 (GND) wires.

Checking Signal and Ground Wires for Mass Air Flow (MAF) Sensor







- Connect VAG 1598/31 adapter cable 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 short circuits to B+ or Ground (GND).

If no DTCs are found in wires:
- Replace Mass Air Flow (MAF) sensor -G70-