With Manufacturer's Scan Tool

Mass Air Flow (MAF) Sensor, Checking

Special tools and equipment
- V.A.G1551 scan tool or V.A.G1552 mobile scan tool with V.A.G1551/3B cable
- V.A.G1598/31 test box
- V.A.G1526 or Fluke 83 multimeter
- V.A.G1594 adapter set
- Wiring diagram

Check conditions







- All fuses must be OK.
- Coolant temperature must be at least 80 degrees C, see display group 04, display zone 3.
- All electrical consumers, e.g. lights and rear window defroster 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 V.A.G1551 scan tool (V.A.G1552). Start engine and select "Address word" 01 of engine control module. Engine must be running at idling speed. (Connecting scan tool and selecting engine control module. [1][2][3]Connecting VAG 1551 Scan Tool)

Indicated on display:

Rapid data transfer HELP
Select function XX

- Press keys 0 and 8 for 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 to 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 to 4.5 g/s

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

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

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

Checking voltage supply for Mass Air Flow (MAF) sensor







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

If no voltage is present:
- Switch ignition off.
- Check wiring from contact 2 to fuel pump (FP) 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 (GND):
Specification: 4.5 to 5.5 V

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

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







- Connect V.A.G1598/31 test box 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 5 + socket 29
Contact 3 + socket 27
Wire resistance: Max. 1.5 Ohms

- Check wires for short to one another.
- Check wiring for short to battery positive or Ground (GND).

If no wiring malfunction is detected:
- Replace Mass Air Flow (MAF) sensor -G70-.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory. DTC Memory, Checking and Erasing (Functions 02 and 05)
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes