Air Flow Meter/Sensor: Testing and Inspection
Mass Air Flow (MAF) Sensor -G70-, Checking
Special tools and equipment
- VAG1526A
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1
or
- VAG1551 with VAG1551/3B
Test requirements:
- Coolant temperature at least 80 degree 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. Connecting VAS 5051/VAG1551 Scan Tool
Engine must run at idle for this.
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 -N80- is closed and the A/C compressor is switched off
Indicated on display:
System in 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.
Indicated on display:
System in Basic Setting 2 ->
1 2 3 4
- Check specified values for load detection.
Display Group 002:
If specified value is obtained:
- Press -> button.
Indicated on display (function selection):
Rapid data transfer HELP
Select function XX
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.
Harness connector Measure to
Terminal
2 Engine Ground (GND)
- 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 2 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 3 of connector.
If specified value is not obtained:
- Check wire connections.
- Connect multimeter to terminal 3 and terminal 4 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. Wiring and Component Testing Using VAG1598/31 Test Box
- Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:
Harness connector VAG1598/31 test box
Terminal Socket
3 27
4 53
5 29
- 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-.