With Manufacturer's Scan Tool
Mass Air Flow (MAF) Sensor -G70-, Checking
ECM uses MAF Sensor -G70- signal to calculate injection quantity and for regulating EGR. The smaller the -G70- signal; the smaller the quantity of injected fuel.
Special tools
- VAG 1551/1552 Scan Tool using VAG 1551/3 Adapter cable
- VAG 1598/22 Test Box (MY 1999)
- VAG 1598/31 Test Box (from MY 2000)
- Fluke 83 multimeter
- VW 1594 Adapter kit
- Wiring diagram
WARNING!
For safe operation, use a second technician to operate test equipment and take readings from back seat, during test drive.
Test sequence
- Connect VAG 1551/1552 Scan Tool and start engine and let idle.
- Press 0 and 1 buttons to select Address word 01: "Engine electronics"
Display will appear as shown (example only)
038906018M 1.9l R4 EDC 00AG 1813 ->
Coding 0001 WSC XXXXX
- Press -> button.
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Press 0 and 8 buttons to select Function 08: "Read measuring value block".
- Press Q button to enter input.
Display will appear as shown
Read measuring value block HELP
Input Display group number XXX
- Press 0,1 and 0 buttons to select "Display group 10".
- Observe display in Display zone 1.
Specified Value: 200 to 450 mg/H
Read measuring value block 10 ->
309 mg/H 1027 mbar 1011 mbar 0.0 %
If specification not obtained
- Check Exhaust Gas Recirculation system
If specification obtained
- Accelerate vehicle in 3rd gear from about 1500 rpm under Wide Open Throttle.
- Press PRINT button on VAG 1551 at approx. 3000 rpm.
- Specification in Display zone 4:100 % (Throttle position)
Read measuring value block 10 ->
830 mg/H 1027 mbar 1850 mbar 100 %
If specification not obtained
- Repeat test and accelerate vehicle under Wide Open Throttle.
Specification in Display zone 1: above 800 mg/H
Read measuring value block 10 ->
830 mg/H 1027 mbar 1850 mbar 100 %
If specification not obtained
- Replace Mass Air Flow Sensor -G70-
- Display the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If DTC memory was erased
- Set the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If 550 mg/H is constantly displayed in zone 1.
- Press -> button.
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Press 0 and 6 buttons to select Function 06: "End output".
- Press Q button to enter input.
- Switch OFF ignition.
- Disconnect -G70- harness connector.
- Switch ON ignition.
- Switch multimeter to 20 Volt range.
- Measure -G70- voltage supply between the following connector terminals:
Terminal: -G70- Specification
2 + Ground App. battery Voltage
2 + 3 App. battery Voltage
4 + Ground Approx. 5 Volts
4 + 3 Approx. 5 Volts
If specifications not obtained
- Switch OFF ignition.
- Connect VAG 1598/22 (or 1598/31) Test Box to ECM wiring harness.
- Check wiring for open circuit between Test Box and connections using Wiring diagram.
Up to MY 1999
- Terminal 2 + socket 2 and 28
- Terminal 3 + socket 4
- Terminal 4 + socket 50
- Terminal 5 + socket 52
From MY 2000
- Terminal 2 + socket 1 and 2
- Terminal 3 + socket 49
- Terminal 4 + socket 30
- Terminal 5 + socket 68
- Wire resistance: 1.5 Ohms maximum
- Check wires for short to one another, to Ground and to Battery +
Specification: Infinity Ohms
If wiring OK
- Replace Engine Control Module -J248-
- Display the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If DTC memory was erased
- Set the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes