Mass Air Flow (MAF) Sensor 2, Checking
Mass Air Flow (MAF) Sensor 2, Checking
• Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor2 (G246).
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• The Mass Air Flow (MAF) Sensor 2 (G246) 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
Function test
- 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 2 (G246) 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 2 (G246):
- Check the voltage supply of the Mass Air Flow (MAF) Sensor 2 (G246) => [ Checking voltage supply ] Mass Air Flow Sensor and Intake Air Temperature Sensor, Checking.
If specified value was not obtained:
- Check the wiring of the Mass Air Flow (MAF) Sensor 2 (G246) => [ Checking electrical circuit ] Mass Air Flow Sensor and Intake Air Temperature Sensor, Checking.
Checking voltage supply
- Disconnect the Mass Air Flow (MAF) Sensor 2 (G246) electrical harness connector - 3 -.
- Start the engine and let it run at idle.
- Using a multimeter, check the Mass Air Flow (MAF) Sensor 2 (G246) 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 2 (G246) electrical harness connector terminal 2 to the Fuel Pump (FP) Control Module (J538) terminal 2 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. Refer to appropriate service manual.
If the manufacturers test box is not being used, perform the following step.
- Remove the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service manual.
- Using a multimeter, check the Mass Air Flow (MAF) Sensor 2 (G246) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T94 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.
- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09
- Perform a road test to verify repair.
If the DTC does not return:
Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Programming and Relearning.
If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Motronic Engine Control Module (ECM) (J623).Refer to appropriate service manual.
- Assembly is performed in the reverse of the removal.
Final procedures
After 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 - 09.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Programming and Relearning.