Mass Air Flow Sensor, Checking
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 connections between engine/transmission/chassis OK.
• Coolant Temperature at least 80° C.
• Ignition switched OFF.
Test procedure
- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions
- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions
- 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 (G70) at idle:
- Switch ignition OFF.
If the specified value was obtained, but the DTC memory has a DTC concerning the Mass Air Flow (MAF) Sensor (G70):
Checking Power Supply:
- Disconnect the Mass Air Flow (MAF) Sensor (G70) electrical harness connector.
- Start the engine and let it run at idle.
- Using a multimeter, check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminal 1 to engine ground.
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 1 to fuse S10 for high resistance, an open or short to ground.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If specified value was obtained:
Checking voltage:
- Turn the ignition ON.
- Using a multimeter, check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminals to engine ground for voltage.
Specified values: voltage should be NEAR the values in the chart below.
If all of the specified values were obtained:
- Replace the Mass Air Flow (MAF) Sensor (G70). Refer to the Repair Information.
If any of the specified values were Not obtained:
Checking electrical circuit:
- Remove the 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 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 high resistance, an open or a short to voltage or 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 the voltage supply was Not OK:
- Replace the Engine Control Module (ECM) (J623). Refer to the Repair Information.
- 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. 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 ] Monitors, Trips, Drive Cycles and Readiness Codes.