Mass Air Flow (MAF) Sensor G70, Checking

Mass Air Flow (MAF) Sensor G70, Checking

Special tools, testers and auxiliary items required
- Multimeter V.A.G 1526 or equivalent.
- Test Box 105 Pin VAG1598/42.
- Adapter Lead Vag1598/39 VAG1598/39.
- Adapter cable V.A.G 1598/39-1.

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

Test requirements
- Fuse for Mass Air Flow (MAF) Sensor G70 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 degrees C.
- Ignition switched off.

Function test
- Connect the diagnostic tester.
- Start engine and let it run at idle.
- Select "Diagnostic mode 1: Check measured values".
- Select measuring value "PID 16: Air stream amount at Mass Air Flow (MAF) sensor".
- Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor G70 at idle:







- End diagnosis and switch ignition off.

If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) Sensor G70 :
- Check voltage supply of Mass Air Flow (MAF) Sensor G70.

If specified value is not obtained:
- Check wiring of Mass Air Flow (MAF) Sensor G70.

Checking voltage supply







- Disconnect the electrical harness connector - 1 - from the Mass Air Flow (MAF) Sensor G70.
- Start engine and let it run at idle.







- Using the Multimeter V.A.G. 1526 A or equivalent, check the Mass Air Flow (MAF) Sensor G70 electrical connector terminal 3 to engine Ground (GND) for voltage.
Specified value: battery voltage
- Switch ignition off.

If the specified value is not obtained:
- Check wiring between Mass Air Flow (MAF) Sensor G70 electrical connector terminal 3 and Engine Component Power Supply Relay J757 for an open circuit.
Specified resistance 1.5 Ohms max.

If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring
- Connect the Test Box 105 Pin VAG1598/42 to the wiring harness of the Engine Control Module (ECM) J623. The ECM is not connected.







- Using the Test Box 105 Pin VAG1598/42 and Multimeter V.A.G 1526 A or equivalent, check the following wiring connection for an open circuit.

Terminal Test box socket
1 22
2 1
2 2
2 4
3 87

Specified resistance 1.5 Ohms max.

If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:
- Replace Mass Air Flow (MAF) Sensor G70.

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

- End diagnosis and switch the ignition off.