With Manufacturer's Scan Tool
Mass Air Flow Sensor -G70-, Checking
NOTE: Only gold plated terminals may be used to service terminals in the Mass Air Flow (MAF) sensor connector.
Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG 1551 Scan tool (or VAG 1552) with VAG 1551/3 adapter cable
NOTE: All functions which could previously be performed with VAG 1551/1552 can also be performed with the VAS 5051.
- VAG 1526 Hand multimeter or VAG 1715 multimeter
- VAG 1594 Adapter set
- VAG 1598/31 Test box
- Electrical Wiring Diagrams
Test prerequisites
- The fuses must be OK.
- The battery voltage must be at least 11.5 V.
- All electrical accessories, e.g. lights and rear window heating must be switched off.
- If the vehicle is equipped with air conditioning, it must be turned off.
- Selector lever must be in position "P" or "N" on vehicles with an automatic transmission.
- Fuel Pump (FP) -J17- must be OK., checking:
- Coolant temperature must be at least 85 degrees C, See display group 1, display zone 2.
Test sequence
- Connect VAG 1551 Scan tool (or VAG 1552) and select engine electronics control module with the "Address word" 01. When doing this the engine must be running at idle speed: ((VAG 1551 and Motronic Engine Control Module (ECM) -J220-, connecting and selecting).
[1][2][3]Connecting VAG 1551 Scan Tool
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- for function "Read measured value (data) block" and confirm entry with -Q- button.
Indicated on display:
Read measured value block
Input display group number XXX
- Press buttons -0-, -0- and -2- for "Display group number 2" and confirm entry with -Q- button.
Indicated on display: (1...4 = display zones)
Read measured value block 2 ->
1 2 3 4
- Check the mass of air drawn in, in display zone 4
Specification: 3.0 to 5.0 g/s
- Press the -> button.
- Press buttons -0- and -6- for function "End output" and confirm entry with the -Q- button.
- Switch off ignition.
If the specification is achieved but an Mass Air Flow (MAF) related Diagnostic Trouble Code (DTC) is registered in Diagnostic Trouble Code (DTC) memory:
- Check voltage supply for Mass Air Flow (MAF) sensor -G70-.
Testing and Inspection
If the specification is not obtained:
- Check the signal and ground (GND) wires for Mass Air Flow (MAF) sensor -G70-.
Testing and Inspection
Checking voltage supply for Mass Air Flow (MAF) sensor
- Pull 5-pin connector off Mass Air Flow (MAF) sensor -G70- with Intake Air Temperature (IAT) sensor -G42- -arrow-.
- Connect multimeter to measure voltage at connector terminal 2 and engine ground (GND).
- Start engine and run at idle speed.
Specification: 11.0 to 15.0 V
- Switch off ignition.
If no voltage is present:
- Check wire for open circuit between 5-pin connector terminal 2 and Fuel Pump (FP) -J17- referring to Electrical Wiring Diagrams.
Wire resistance: max. 1.5 ohms
If the voltage supply and wiring is OK.:
- Connect multimeter to measure voltage at connector terminal 4 and engine ground (GND).
- Switch on ignition
Specification: at least 4.5 V
- Switch off ignition.
If no voltage is present:
- Check the signal and ground (GND) wires for Mass Air Flow (MAF) sensor.
Testing and Inspection
Checking signal and ground (GND) wires for Mass Air Flow (MAF) sensor
- Remove wiper arms and cowl panel:
- Connect VAG 1598/31 test box to control module wiring harness. The Motronic Engine Control Module (ECM) -J220- remains disconnected.
- Check wiring for open circuit between test box and 5-pin connector referring to Electrical Wiring Diagrams.
Terminal 3 and socket 27
Terminal 4 and socket 53
Terminal 5 and socket 29
Wire resistance: max. 1.5 ohms
- Additionally check wiring for short to one another, to vehicle ground (GND) and to battery positive.
Specification: infinity ohms
If no wiring malfunction is detected:
- Replace Mass Air Flow (MAF) sensor -G70-, item 6.
- Check DTC memory, repair malfunctions if necessary and then erase DTC memory
Reading Diagnostic Trouble Codes.
- Read readiness code. If the DTC memory has been erased or the Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes