Air Flow Meter/Sensor: Testing and Inspection
MASS AIR FLOW SENSOR, CHECKING
Special tools, testers and auxiliary items
- VAG 1551/1552 scan tool with VAG 1551/3 adapter cable
- VAG 1598/18 test box
- Multimeter (Fluke 83 or equivalent)
- Connector test kit VW 1594
- Wiring diagram
Test conditions
- Electrical consumers switched off (radiator coolant fan must not run during the check)
- A/C switched off
Test sequence
- Engine running at idle
- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01. Refer to "On-Board Diagnostics II With VAG 1551". 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-, -1- and -5- for display group number 015 and press -Q- button to confirm input.
Indicated on display (1-4 = Display fields)
Read Measuring Value Block 15 ->
1 2 3 4
- Check the load registration 1 specifications (display fields 2 and 3):
- Press -C- button.
- Press buttons -0-, -1- and -6- for display group number 016 and press -Q- button to confirm input.
Indicated on display (1-4 = Display fields)
Read Measuring Value Block 16 ->
1 2 3 4
- Check the load registration specifications 2 (display field 3):
Evaluating Display Group 016:
Checking Voltage Supply:
- Disconnect 4-pin connector from Mass Air Flow (MAF) sensor.
- Connect multimeter with test leads from VW 1594 to measure voltage at terminals 1 and 3.
Specification: 9.0-14.5 volts
If no voltage is present:
- Switch ignition off.
- Check wiring according to wiring diagram.
Checking Wiring
- Switch ignition off.
- Connect VAG 1598/18 test box to ECM wiring harness.
- Check wiring between test box and 4-pin connector for open circuit according to wiring diagram.
- Terminal 2 and test box socket 16
- Terminal 4 and test box socket 17
Resistance: maximum 1.5 Ohms
- Additionally, check 4-pin connector terminals for short circuit to one another.
Terminal 4 and test box socket 16
Specification: Infinity Ohms
- Set multimeter to voltage measurement range.
- Check 4-pin connector terminals for short circuit to battery positive (B+) according to wiring diagram.
- Terminal 2 and vehicle Ground (GND)
- Terminal 4 and vehicle Ground (GND)
Specification: 0 volts
If no wiring malfunction is detected:
- Replace Mass Air Flow (MAF) sensor -G70-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group, see Readiness code, creating. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection