MAF Sensor, Checking

Diagnostic Procedures

MAF 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 1 in Fuse Panel C is 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 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 it run at idle.

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





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

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

If the specified value was Not obtained:

Checking voltage supply

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





- 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.





Specified value: Battery voltage.

- Switch the ignition OFF.

If the specified value was Not obtained:

- Remove the fuse 1 in Fuse Panel C. Check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminal 3 to Fuse 1 in Fuse Panel C for an open circuit.

Specified value: 1.5 ohms max.

If the specified value was obtained:

Checking electrical circuit

If the manufacturers test box is being used, perform the following step.

- Install the test box.

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

- Remove the Motronic Engine Control Module (ECM) ( J623). Refer to the repair information.

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









Specified value: 1.5 ohms max.

If the specified value was Not obtained:

- 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.

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

- Replace Mass Air Flow (MAF) Sensor (G70) Refer to the repair information.

If no malfunction is detected in the wiring and if the voltage supply was Not OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the repair information.

Final procedures

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 ] Scan Tool Testing and Procedures.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Scan Tool Testing and Procedures.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.