Air Flow Meter/Sensor: Testing and Inspection

Test conditions
- Coolant Temperature less than 80 °C
- Electrical consumers switched oft (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 VAG 1551 scan tool and select control module for engine electronics using "address word" 01.
- 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 "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


- Press buttons - 0-, -0- and -2- to select "display group number 002" and press -Q- button to confirm input.

Indicated on display:


Basic Setting 2 ->
1 2 3 4


- Check specified values for load detection.

Display Group 2:

If specified value is obtained:
- Press -> button.

Indicated on display (function selection)


Rapid data transfer HELP
Select function XX


Evaluation Display Group 002

Display Field 3:

Display Field 4:

Check voltage supply for Mass Air Flow (MAF) sensor







- Disconnect connector at Mass Air Flow (MAF) sensor.
- Connect multimeter for voltage measurement as follows.

Harness connector terminal Measure to
2 Engine Ground

- Operate starter briefly.
- Specification: approx. battery voltage


NOTE: Voltage is supplied to Mass Air Flow (MAF) sensor via 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.
- 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 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.
- Specification: approx. 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 VAG 1598/31 test box at wiring harness to ECM, do not connect ECM.







- Check the following wire connections for open circuit and short circuit to Ground and B+:

Harness connector terminal VAG 1598/31 test box 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 -.