Air Flow Meter/Sensor: Testing and Inspection
Mass Air Flow (MAF) Sensor G70 , Checking
Special tools, testers and auxiliary items required
- Multimeter.
- wiring diagram
- The manufacturers test box Adapter Cable (121-point) VAG1598/31 is available for purchase or rental. Refer to the Tool catalog .
NOTE:
- All manufacturers special tools as well as common tools may contain a manufacturer specific part number. These tools may be substituted with an equivalent aftermarket tool, or are available for purchase from the manufacturer.
- Manufacturers special tools as well as common tools that contain a manufacturer specific part number may be referenced in the test procedure illustrations, showing the tool use or installation. If the manufacturer specific tool is not being used, an equivalent aftermarket tool may be installed in the same manner as the manufacturers special tool.
- Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor G70.
Test requirements
- Fuse for Mass Air Flow (MAF) Sensor G70 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 (GND) connections between engine/transmission/chassis OK.
- Coolant Temperature at least 80 degrees C.
- Ignition switched off.
Function test
- Connect the scan tool.
- Start engine and let it run at idle.
- Select "Diagnostic mode 1: Check measured values".
- Select measuring value "PID 16: Air stream amount at Mass Air Flow (MAF) sensor".
- Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor G70 at idle:
- End diagnosis and switch ignition off.
If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) Sensor G70 :
- Check voltage supply of Mass Air Flow (MAF) Sensor G70 .
If specified value is not obtained:
- check sensor internal resistance:
Pin numbers: Value:
1 to 3 2 kOhms
1 to 4 6 kOhms
1 to 5 297 kOhms
3 to 4 4.5 kOhms
3 to 5 297 kOhms
4 to 5 900 kOhms
- values obtained, continue diagnosis
- Values not obtained, replace sensor G70.
- Check wiring of Mass Air Flow (MAF) Sensor G70 .
Checking voltage supply
- Disconnect the electrical harness connector - 1 - from the Mass Air Flow (MAF) Sensor G70.
- Start engine and let it run at idle.
- Using a Multimeter, check the Mass Air Flow (MAF) Sensor G70 electrical connector terminal 2 to engine Ground (GND) for voltage.
Specified value: battery voltage
- Switch ignition off.
If the specified value is not obtained:
- Check the electrical harness connector for damage, corrosion, lose or broken terminals.
- Check wiring between Mass Air Flow (MAF) Sensor G70 electrical connector terminal 2 and Engine Component Power Supply Relay J682 for an open circuit.
Specified resistance 1.5 Ohms max.
If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.
If no malfunctions are found in the wiring:
Checking wiring
- Using a Multimeter, check the following wiring connection for an open circuit.
Mass Air Flow Sensor G70 Motronic Engine Control Module (ECM)
electrical harness connector J623 electrical connector T121 terminal or
terminal test box socket
1 6
2 Fuse 29 (on fuse panel C, in cabin, L.H. side)
3 27
4 53
5 29
Specified resistance 1.5 Ohms max.
If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.
If no malfunctions are found in the wiring:
- Replace Mass Air Flow (MAF) Sensor G70.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.
- End of diagnosis.