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

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







Special tools and equipment
- VAG 1526 A
- VAG1594A
- VAG 1598/31
- VAS 5051 with VAS 5051/1

Requirements for test:
- Coolant temperature at least 80 degrees 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, Vehicle Diagnostic, Testing and Information System VAS 5051, Connecting and Selecting Functions , and select the vehicle system "01 - Engine electronics" from the menu. When doing this the engine should be idling.







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-.







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.

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 Contact Measure against
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. Scan Tool Testing and Procedures







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

Connector connect Test box VAG1598/31
Terminal 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-.