With Manufacturer's Scan Tool

Mass Air Flow (MAF) Sensor -G70-, Checking

Special tools and equipment







- VAG1526A
- VAG1594A
- VAG1598/31
- VAS5051 with VAG5051/1

Test requirements:
- Coolant temperature at least 80 degree C.
- Electrical consumers switched off (radiator fan must NOT run during test).
- A/C switched off.

Checking function
- Connect VAS5051 tester scan tool and select the control module for engine electronics using "address word" 01. Engine must run at idle for this. Connecting VAS 5051/VAG 1551 Scan Tool (ST)

Display on VAS 5051:







- Select "04 - Basic setting."

Display on VAS 5051:







1 - Enter display group, max. entered value = 255
- In display field -2- enter "002" to select "display group number 002" and press -Q- button to confirm input.

Indicated on display:







- Check specified values for load detection in display fields -3- and -4-.

Display Group 002:

If specified value is obtained:
- Exit function "04 - Basic setting" by pressing <- button.







Voltage Supply For Mass Air Flow (MAF) Sensor, Checking

Test requirements:
- Fuse for Mass Air Flow (MAF) sensor OK.
- Fuel pump relay OK. Testing and Inspection

NOTE: Voltage supply to Mass Air Flow (MAF) sensor is from Fuel Pump (FP) Relay -J17-.

- Disconnect connector (arrow) to Mass Air Flow (MAF) sensor







- Connect the multimeter to the following:

Harness connector Measure to
Terminal
2 Engine Ground (GND)

- Operate starter briefly (engine can be started).
- Specification: approx. battery voltage

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 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. Electrical 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-.