With Manufacturer's Scan Tool

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







Special tools and workshop equipment required
- V.A.G 1526 A Multimeter
- V.A.G 1594 A Connector test kit
- V.A.G 1598/31 Test Box
- VAS 5051 Vehicle diagnostic, testing and information system
- VAS 5051/1 Adapter
- Component location

Requirements
- Coolant temperature at least 80 degrees C.
- Electrical consumers switched off (coolant fan must not run during the test).
- Air conditioning switched off.

Checking function
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" in selection. Engine must be run at idle speed.







Display on VAS 5051:
- Under -1- select diagnostic function "04 - Basic setting".







Display on VAS 5051:
1. Enter display group
- Enter "002" for "display group number 002" in zone -2- and confirm entry by pressing -Q- button.







Display on VAS 5051:
- Activate basic setting by pressing -A- button.
- Check indication in display fields -3- and -4-.







- Exit function "04 - Basic setting" by pressing button.

Evaluation of display group 002







Voltage supply to Mass Air Flow (MAF) sensor -G70-, testing

Requirements
- Fuse for Mass Air Flow (MAF) sensor OK.
- Fuel pump relay OK; checking. With Generic Scan Tool

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 multimeter as follows to measure voltage.

Connector terminal Measure to
2 Engine ground

- Operate starter briefly.

Specified value: approx. battery voltage (B+)

If specified value is not obtained:
- Check wiring from terminal 2 on connector via fuse to fuel pump relay for open circuit or short to ground:
- Repair any open/short circuit as necessary.

If specified value is obtained:







- Connect hand-held multimeter to terminals 2 and 3 of connector to measure voltage.
- Operate starter briefly (engine may start).

Specified value: approx. battery voltage (B+)

NOTE: Engine control module ground (GND) is present at terminal 3 of the connector.

If specified value is not obtained:
- Check wiring







- Connect hand-held multimeter to terminals 3 and 4 of connector to measure voltage.

Specified value: approx. 5 V

If specified value is not obtained:
- Check wiring

Wiring to Mass Air Flow (MAF) sensor -G70-, checking

NOTE: The signal wire is also checked during the wiring check.

- Connect test box V.A.G 1598/31 to wiring harness for Engine Control Module (ECM); do not connect Engine Control Module (ECM). Test Box, Connecting For Wiring and Component Test







- Check for open circuit, short to positive, or short to ground (GND) in following wiring connections:

Connector terminal Test box V.A.G 1598/31 Socket
3 27
4 53
5 29

- Repair any open/short circuit as necessary.
- Additionally check all wires for short to one another.

If the wiring is OK:
- Replace Mass Air Flow (MAF) sensor -G70-.