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). [1][2][3]Connecting VAG 1551 Scan Tool

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-