Mass Air Flow Sensor, Checking

Mass Air Flow Sensor, 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
- Fuse S243 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.

Test procedure
- Perform a preliminary check to verify the customers complaint. General Diagnosis

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:

Diagnostic text Specified value
Air flow quantity at Mass
Air Flow (MAF) sensor
Engine running at idle 2.00 to 5.00 g/sec

- 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 was not obtained:
- Check the Mass Air Flow (MAF) Sensor G70 electrical circuit.

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 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 3 to the Ignition/Starter Switch D terminal 6/15 for an open circuit, a short circuit to each other, Battery (+), and Ground (GND).

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

Checking Ground (GND)







- Using a multimeter , check the Mass Air Flow (MAF) Sensor G70 electrical harness connector terminal 2 to Ground (GND) location in engine compartment left for resistance.

Specified value: 1.5 Ohms max.

If the specification is not obtained:
- Check the Mass Air Flow (MAF) Sensor G70 electrical harness connector terminal 2 to Ground (GND) location in engine compartment left for an open circuit, a short circuit to each other, Battery (+), and Ground (GND).
- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:.

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 Engine Control Module (ECM) J623.







- Using a multimeter , check the Mass Air Flow (MAF) Sensor G70 electrical harness connector terminal to the Engine Control Module (ECM) J623 electrical harness connector T94 terminal for resistance.

Mass Air Flow (MAF) Sensor Engine Control Module (ECM) J623
G70 electrical harness electrical harness connector T94
connector terminals terminals or test box socket
1 22

Specified value: 1.5 Ohms max.

If the specification is not obtained:
- Check the wiring for an open circuit, 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.
- Erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and voltage supply was OK:
- Replace the Engine Control Module (ECM) J623.
- Assembly is performed in the reverse of the removal.

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of diagnosis