MAF Sensor, Checking: Notes

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Mass Air Flow (MAF) Sensor -G70- fuse 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 

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 warmed up, running at idle	2.00 to 5.00 g/sec

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

-- Fault may be intermittent. Check the electrical harness connector for damage, corrosion, loose or broken terminals.

If the specified value was Not obtained: 

Checking voltage 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 3 to engine Ground.

Specified value: Battery voltage.

-- Switch the ignition OFF.

Continue test according to the following table: 

Value	Cause	Test
If the specified value was not obtained:	Open or shorted circuit	Checking wiring
If the specified value was obtained:	Check reference signal circuit	Check reference signal