Air Flow Meter/Sensor: Testing and Inspection
Mass Air Flow (MAF) Sensor -G70-, Checking
Special and Equipment
- VAG1526A
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1
- or
- VAG1551 with VAG1551/3B
Test requirements:
- Coolant Temperature at least 80 °C.
- Electrical consumers switched off (radiator fan must NOT run during test).
- A/C switched off.
- Fuse for Mass Air Flow (MAF) sensor OK
Checking function
- Connect VAS5051 tester or VAG1551 scan tool and select the control module for engine electronics using "address word" 01. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAS5051/VAG1551 Scan Tool" Testing and Inspection
Engine must run at idle for this.
When indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -4- to select "Initiate basic setting" and press -Q- button to confirm input.
Note: During basic setting, the Evaporative Emission (EVAP) canister purge regulator valve (EVAP valve -N80-) is closed and the A/C compressor is switched off
When indicated on display:
Basic Setting Q
Input display group number XXX
- Press buttons -0-, -0- and -2- to select "display group number 002" and press - Q- button to confirm input.
When indicated on display:
System in Basic Setting 2 ->
1 2 3 4
- Check specified values for load detection in display fields 3 and 4.
Display group 002:
If specified values are obtained:
- Press -> button.
Indicated on display (function selection):
Rapid data transfer HELP
Select function XX
Evaluation display group 002
Evaluation display group 002
Voltage supply for Mass Air Flow (MAF) sensor, checking
- Disconnect connector from Mass Air Flow (MAF) sensor.
- Connect multimeter for voltage measurement as follows.
- Operate starter briefly.
- Specification:approx.battery voltage
NOTE: Voltage is supplied to Mass Air Flow (MAF) sensor from Fuel Pump (FP) relay.
If specified value is not obtained:
- Check wire connection from terminal 3 of connector to Fuel Pump (FP) relay via fuse for open circuit and short circuit to Ground (GND):
- Repair open circuit or short circuit if necessary.
- Connect multimeter to terminal 2 and terminal 3 of connector for voltage measurement.
- Operate starter briefly.
- Specification: approx. battery voltage
NOTE: Ground (GND) from the ECM is present at terminal 2 of Connector.
If specified value is not obtained:
- Check wire connections.
- Connect multimeter to terminal 1 and terminal 2 of connector for voltage measurement.
- Switch ignition on.
- Specification: about 5 V
If specified value is not obtained:
- Check wire connections.
Check wire connections for Mass Air Flow (MAF) sensor
NOTE: Signal wire is also checked during wire test.
- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" Testing and Inspection
- Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:
- Repair open circuit or short circuit if necessary.
- Also check all wires for short circuit to each other.
If wire connection is OK:
- Replace Mass Air Flow (MAF) sensor -G70-.