Air Flow Meter/Sensor: Testing and Inspection
Mass Air Flow (MAF) Sensor, Checking
Required special tools and test equipment
- VAG 1551 or VAG 1552 Scan Tool (ST) with VAG 1551/3 adapter cable
- VAG 1598/22 test box
- Multimeter US 1119 (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagram
Test requirements
- All electrical consumers switched off (coolant fan must not run during test).
- A/C must be switched off
- Fuse for MAF sensor OK
Test sequence
- Connect VAG 1551 or VAG 1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (with engine running at idle). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551/1552 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, and press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block HELP
Input display group number XXX
- Press buttons -0-, -0- and -2- to input display group number 2, and press -Q- button to confirm input.
Indicated on display (1-4 = display fields)
Read Measuring Value Block 2 ->
1 2 3 4
- Compare display with specified values for engine load (display fields 2 and 4):
Display Group 2:
If displayed values are OK (as specified):
- Press -> button to advance program sequence.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.
- Switch ignition off.
Evaluation of display group 2
Display Field 2:
Checking voltage supply
- Disconnect 4-pin harness connector from Mass Air Flow sensor (MAF).
- Connect multimeter US 1119 (Fluke 83 or equivalent) between harness connector terminals 1 and 3 (to ECM), using adapter cables from VW 1594 connector test kit.
Specified value: 9.0 - 14.5 volts
If there is no voltage:
- Switch ignition off.
- Check wiring using applicable wiring diagram.
Checking wiring
- Switch ignition off.
- Connect VAG 1598/22 test box to ECM harness connector. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1598/22 Test Box" Testing and Inspection
- Check wiring for open circuits between ECM/test box and 4-pin MAF sensor harness connector.
- Connector terminal 2 to ECM/test box socket 12
- Connector terminal 4 to ECM/test box socket 13
- Specified value: max. 1.5 Ohms
- Check wiring for short circuits between terminals of 4-pin connector, and between connector and ECM/test box.
- Connector terminal 4 to ECM/test box socket 12
- Specified value: Infinity Ohms
- Switch multimeter to 20 VDC measuring range.
- Check wiring at 4-pin connector for short circuit to B+ (battery positive voltage), according to applicable wiring diagram.
- Connector terminal 2 to vehicle Ground
- Connector terminal 4 to vehicle Ground
- Specified value: 0 volts
If wiring is OK:
- Replace Mass Air Flow sensor (MAF) -G70-.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.
Refer to "Monitors, Trips and/or Drive Cycle/Displaying Readiness Code" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection