MAF Sensor, Checking

Special tools and workshop equipment 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 

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

-- Turn the ignition switch OFF.

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.

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, high resistance or short to ground.

-- Repair the circuit as necessary. Refer to the appropriate SYSTEM WIRING DIAGRAMS information.

If the specified value was obtained: 

-- Turn the ignition switch On.

-- Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 1 to engine Ground.

Specified value: Near 4.90 V.

-- Switch the ignition OFF.

If the specified value was 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 terminals for an open circuit. Refer to the appropriate SYSTEM WIRING DIAGRAMS information.

For 2008 - 2010 Passat: 

Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals:	Engine Control Module (ECM) -J623- electrical connector T94 terminals:
1	23
2	65
3	fuse SC-10
4	12
5	60

For 2010 > CC: 

Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals:	Engine Control Module (ECM) -J623- electrical connector T94 terminals:
1	23
2	65
3	fuse SC-10

Specified value: 1.5 Ω 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 the terminal 1 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 the terminal 1 voltage supply was Not OK: 

-- Replace the 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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .