Air Flow Meter/Sensor: Testing and Inspection
Mass Air Flow (MAF) Sensor, Checking
Special tools and equipment
- VAG 1551 Scan Tool or VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/22
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram
Check conditions
- Coolant temperature must be at least 80 degree 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 VAG 1551 Scan Tool ((VAG 1552). Start engine and select "Address word" 01 of engine control module. Engine must be running at idle speed. (Connecting scan tool and selecting engine control module [1][2][3]Connecting VAG Scan Tool 1551/1552).
Indicated on display
Rapid data transfer HELP
Select function XX
- Press keys 0 and 8 for function "Read Measuring Value Block" and confirm entry with Q key.
Indicated on display
Read Measuring Value Block HELP
Input display group number XXX
- Press keys 0, 0 and 5 for "Display group number 5" and confirm entry with Q key.
Indicated on display: (1 to 4 = Display zones)
Read Measuring Value Block 5 ->
1 2 3 4
- Observe idling switch operating mode in display zone 4. As long as engine is running at idling, idling must be displayed
Display: Idling
If the specification is not obtained:
- Check idling switch, checking throttle valve control module. Throttle Valve Control Module, Checking
If the specification is obtained:
- Press C key.
- 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 Measuring Value Block 2 ->
1 2 3 4
- Check mass of air drawn in in display zone 4
Specification: 2.0 to 5.0 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 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.
Testing power supply to 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 idle 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:
Specification: 4.5 to 5.5 V
If no voltage is present:
- Switch ignition off.
- Check signal and Ground wires.
Testing signal and Ground wires for Mass Air Flow (MAF) sensor
- Connect test box VAG 1598/22 to control module wiring harness.
- Check wiring between test box and 5 pin connector for open circuit using wiring diagram.
Contact 5 + socket 13
Contact 4 + socket 11
Contact 3 + socket 12
Wire resistance: Max. 1.5 Ohm
- Additionally check wires all for short to one another.
Specification: Infinite Ohm
- Additionally check the wiring for short to battery positive or Ground.
If no wiring malfunction is detected:
- Replace Mass Air Flow (MAF) sensor -G70-.