Air Flow Meter/Sensor: Testing and Inspection

Mass Air Flow Sensor, Checking

• 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. Refer to => [ Preliminary Check ] Preliminary Check

Start diagnosis

- Connect the scan tool.

- Start engine and let idle.

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






- Switch the ignition OFF.

If the specified value was obtained:

- Condition may be intermittent

- Check the wiring for an open, high resistance or short to ground.

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

- If necessary, repair the faulty wiring connection.

- Go to Final procedures

If the specified value was Not obtained:

- Disconnect the Mass Air Flow (MAF) Sensor (G70) electrical harness connector - 1 -.






- Using a Multimeter, Check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminal 3 to Ground (GND) for voltage.






Specified value: Battery Voltage

- Switch the ignition OFF.

- Continue test according to the following table:






Checking wiring

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service manual.

- Using a Multimeter, Check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector to the Motronic Engine Control Module (ECM) electrical harness connector T94 for an open circuit.











Specified value: 1.5 ohms Max.

If the specified value was Not obtained:

- Check the wiring connection for an open or short circuit.

- Check the wiring connection for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection and replace any open fuses

- Go to Final procedures

If the specified value was obtained:

- If necessary, repair any faulty wiring or connections, If no faults were found Replace the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service manual.

- Go to Final procedures

Checking wiring

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service manual.

- Using a Multimeter, Check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T94 for an open circuit.











Specified value: 1.5 ohms Max.

If the specified value was Not obtained:

- Check the wiring connection for an open circuit, short circuit to Battery positive or Ground

- Check the wiring connection for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

- Go to Final procedures

If the specified value was obtained:

- Replace the Mass Air Flow (MAF) Sensor (G70). Refer to appropriate service manual.

Final procedures

- Reinstall the engine cover and Air Filter Housing, if necessary. Refer to the appropriate service manual.

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

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 0A.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 0A.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Programming and Relearning.