With Generic Scan Tool

Mass Air Flow (MAF) Sensor G70, checking

Note: Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor G70.

Special tools, testers and auxiliary items required
- Multimeter
- Wiring diagram

Test requirements
- The Mass Air Flow (MAF) Sensor G70 Fuse OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Coolant Temperature at least 80�C.
- Ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint.

Start diagnosis

- Connect the scan tool.

- Start engine and let it run at idle.

- Using the scan tool, Check the air flow quantity of the Mass Air Flow (MAF) Sensor G70 at idle:






- End diagnosis and switch ignition off.

If the specified value was obtained, but the DTC memory has a DTC concerning the Mass Air Flow (MAF) Sensor G70:

- Check the voltage supply of the Mass Air Flow (MAF) Sensor G70.

If specified value was not obtained:

- Check the wiring of the Mass Air Flow (MAF) Sensor G70.

Checking voltage supply

- Disconnect the Mass Air Flow (MAF) Sensor G70 electrical harness connector.

- Start the engine and let it run at idle.






- Using a multimeter, check the Mass Air Flow (MAF) Sensor G70 electrical harness connector terminal 3 to engine Ground (GND).

Specified value: battery voltage.

- Switch the ignition off.

If specified value was not obtained:

- Check the Mass Air Flow (MAF) Sensor G70 electrical harness connector terminal 2 to the Fuel Pump (FP) Relay J17 terminal 16/s for an open circuit.

Specified value: 1.5 Ohms max.

If no malfunction is detected in the wiring and if the voltage supply was OK:

Checking electrical circuit

If the manufacturers test box is being used. Perform the following step.

- Install the Test Box 80 Pin VAG1598/22. Connecting VAG 1598/22 Test Box

If the manufacturers test box is not being used. Perform the following step.

- Remove the Engine Control Module (ECM) J220.






- Using a multimeter, check the Mass Air Flow (MAF) Sensor G70 electrical harness connector terminals to the Engine Control Module (ECM) J220 electrical harness connector T80 terminals for an open circuit.






Specified value: 1.5 Ohms max.

If the specification was not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace Mass Air Flow (MAF) Sensor G70.

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

End of diagnosis.