With Manufacturer's Scan Tool

Mass Air Flow (MAF) sensor, checking

Special tools and equipment
- VAG1551 or VAG1552 Scan Tool (ST) with VAG1551/3 adapter cable
- VAG1598/22 test box
- Multimeter US1119 (Fluke 83 or equivalent)
- VW1594 connector test kit
- Wiring diagram

Checking requirements



- Fuses No.31 and 32 OK
- All electrical consumers switched off (coolant fan must not run during test)
- A/C switched off
- Automatic transmission selector lever in "P" or "N" position
- Engine coolant temperature at least 85 °C (185 °F) See VAG1551 scan tool function 08, display group 004, display field 3

Checking
- Connect VAG1551 or VAG1552 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 VAG1551/VAG1552 Scan Tool" under "Engine", 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 (002), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)


Read Measuring Value Block 2 ->
1 2 3 4


- Check 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





Voltage supply, checking




- Disconnect 3-pin harness connector -1- from Mass Air Flow sensor (MAF) -2-.
- Connect multimeter US1119 (Fluke 83 or equivalent) between harness connector terminal 3 and engine Ground, using adapter cables from VW1594 connector test kit.
- Switch ignition on and measure voltage.
Specified value: min. 11.5 volts
- Switch ignition off.

If the specification is not attained:
- Check wiring from terminal 3 to fuse panel using applicable wiring diagram.


Wiring, checking




- Connect VAG1598/22 test box to ECM harness connector.




- Check wiring for open circuits, between ECM/test box and 3-pin MAF sensor harness connector.
- Connector terminal 1 to ECM/test box socket 13
- Connector terminal 2 to ECM/test box socket 12
- Specified value: max. 1.5 Ohms
- Check wiring for short circuits between terminals of 3-pin connector.
- Specified value: Infinity Ohms

If the voltage supply and wiring is OK:
- Replace Mass Air Flow (MAF) sensor -G70-.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code. Monitors, Trips, Drive Cycles and Readiness Codes