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

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







Special tools and equipment
- VAG1526A or Fluke 83 Multimeter
- VAG1594A Connector test kit
- VAG1598/31 Test box
- VAS5051 Vehicle diagnosis, testing and information system with VAS5051/1 Adapter

Requirements
- Coolant Temperature at least 80 degrees C.
- Electrical consumers switched off (radiator coolant fan must NOT run during test).
- A/C switched off.

Checking function
- Connect VAS5051 tester, Vehicle Diagnostic, Testing and Information System VAS 5051, Connecting and Selecting Functions and select vehicle system "01 - Engine electronics". Engine must run at idle.







Display on VAS5051:
- In selection -1-, click on diagnostic function "04 - Basic Setting".







Display on VAS5051:
1 - Enter display group. Max. input value = 255
- Select function "002" in button field -2- for "display group number 002" and press Q button to confirm input.







Display on VAS5051:
- Check specified values for load detection in display fields 3 and 4.







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

Evaluation for display group 002







Voltage supply for Mass Air Flow (MAF) sensor, checking

Requirements
- Fuse for Mass Air Flow (MAF) sensor OK
- Fuel Pump (FP) Relay OK;

NOTE: Voltage is supplied to the Mass Air Flow (MAF) sensor from the Fuel Pump (FP) relay.

- Disconnect connector from Mass Air Flow (MAF) sensor.







- Connect multimeter for voltage measurement as follows:

Harness connector Terminal Measure to
2 Engine Ground (GND)

- Operate starter briefly (engine can also start).

- Specified value: approx. battery voltage

If specified value is not obtained:
- Check wiring 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 in wiring or short circuit if necessary.







- Connect multimeter to terminal -2- and terminal -3- of connector for voltage measurement.
- Operate starter briefly (engine can also start).

- Specified value: approx. battery voltage

NOTE: Ground (GND) from the ECM is present at terminal -3- of connector.

If specified value is not obtained:
- Check wiring connections.







- Connect multimeter to terminal -3- and terminal -4- of connector for voltage measurement.
- Specified value: about 5 V

If specified value is not obtained:
- Check wiring connections.

Checking wiring connections for Mass Air Flow (MAF) sensor

NOTE: Signal wire is also checked during wiring test.

- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM) but do not connect ECM. Scan Tool Testing and Procedures







- Check following wiring 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 in wiring or short circuit if necessary.
- Also check all wires for short circuit to each other.

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