With Manufacturer's Scan Tool

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

Special tools and equipment






- VAG 1526 A
- VAG 1594 A
- VAG 1598/31
- VAS 5051 with VAS 5051/1

Requirements for test:
- Coolant temperature at least 80 degree C
- Electrical consumers switched off (radiator fan must not run during the test)
- Air conditioner switched off

Testing operation
- Connect the vehicle diagnostic, testing and information system VAS 5051, and select the vehicle system "01 - Engine electronics" from the menu. When doing this the engine should be idling. Connecting VAS 5051/VAG1551 Scan Tool






Display on VAS 5051:
- Select the diagnosis function "04 - Basic settings" from the menu -1-.






Display on VAS 5051:
1 - Enter display group
(figures up to 255)
- Using the keypad -2-, enter "002" to select Display group 002 and confirm entry with Q button.






Display on VAS 5051:
- Check readouts for evaluating engine load in display zones -3- and -4-.

Display Group 002:

If the specification is obtained:
- Press the <- button to exit from diagnosis function "04 - Basic settings".

Reading Display Group 002






Testing power supply to mass air flow sensor

Requirements for test:
- Fuse for mass air flow sensor OK
- Fuel pump relay OK. Testing. With Manufacturer's Scan Tool

NOTE: The mass air flow sensor receives its voltage supply via the fuel pump relay.

- Unplug connector from mass air flow sensor.






- Connect multimeter (voltage measurement range) as follows:

Connector Measure against
Contact
2 Engine Ground

- Operate the starter briefly. (The engine can be allowed to start.)
- Specification: approx. battery voltage

If the specification is not attained:
- Test for open circuit or short to Ground in wiring between fuel pump relay and contact 2 on connector via fuse.
- Correct short circuit or open circuit if necessary.






- Connect hand-held multimeter (voltage measurement range) between contacts 2 and 3 of connector.
- Operate the starter briefly. (The engine can be allowed to start.)
- Specification: approx. battery voltage

NOTE: Contact 3 on the connector is for the Ground connection from the engine control module.

If the specification is not attained:
- Test the wiring.






- Connect hand-held multimeter (voltage measurement range) between contacts 3 and 4 of connector.
- Specification: approx. 5 V

If the specification is not attained:
- Test the wiring.

Testing wiring for mass air flow sensor

NOTE: The wiring test also tests the signal wire.

- Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the engine control module itself. Wiring and Component Testing Using VAG1598/31 Test Box






- Test for open circuit and short to positive or Ground in the following wiring connections:

Connector Test box VAG1598/31
Contact Socket
3 27
4 53
5 29

- Correct short circuit or open circuit if necessary.
- Test all wires for short circuits with each other.

If the wiring is OK:
- Fit a new mass air flow (MAF) sensor -G70-.