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

Mass Air Flow (MAF) Sensor -G70, Checking

NOTE: Read measuring value block display group 2 as described in repair manual and evaluate it. If the suggested repair steps refer to the voltage supply test for the Mass Air Flow (MAF) sensor or the wiring connections from the Mass Air Flow (MAF) sensor to the Engine Control Module (ECM), proceed to the following. Refer to "Scan Tool Testing/Measuring Value Blocks/Reading" Testing and Inspection

Please note the distinction between Mass Air Flow (MAF) sensors made by Bosch and those made by Hitachi (recognizable via the writing on the sensor).

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

NOTE: For Bosch Mass Air Flow (MAF) sensors.

- Disconnect connector from Mass Air Flow (MAF) sensor.
- Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.
- Operate starter briefly
Specification: approx. battery voltage

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

If there is no battery voltage.
- Check wire connection from terminal 2 of connector to Fuel Pump (FP) relay via fuse for open circuit and short circuit to Ground (GND), repair if necessary.

- Connect multimeter to terminal 2 and terminal 3 of connector for voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage

NOTE: Ground (GND) 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 1 of connector for voltage measurement.
- Switch ignition on.
Specification: approx. 5 volts.

If specified value is not obtained, check wire connections.

Wire connections for Mass Air Flow (MAF) sensor, checking (Hitachi MAF sensor)

NOTE: Signal wire is also checked during wire test

- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" Testing and Inspection

- Disconnect connector from Mass Air Flow (MAF) sensor.
- Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage

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

If there is no battery voltage.
- Check wire connection from terminal 2 of connector to Fuel Pump (FP) relay via fuse for open circuit and short circuit to Ground (GND), repair if necessary.

- Connect multimeter to terminal 3 and terminal 4 of connector for voltage measurement.
- Switch ignition on.
Specification: approx. 5 volts.

If specified value is not obtained, check wire connections.

Wire connections for Mass Air Flow (MAF) sensor, checking (Bosch MAF sensor)

NOTE: Signal wire is also checked during wire test

- Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" Testing and Inspection

The following wire connections must be checked for short circuit to B+, Ground (GND) and for open circuit

Connector for Mass VAG1598/31 test box
Air Flow (MAF) terminal
sensor-G70-
3 27
4 53
5 29

Wire resistance: max: 1.5 Ohms

- Also check all wires for short circuit to each other.
Specification: Infinite Ohms (no continuity)
- If the voltage supply and the wire connection are OK, replace Mass Air Flow (MAF) sensor -G70-.