Air Flow Meter/Sensor: Testing and Inspection
Mass Air Flow (MAF) Sensor, Checking
NOTE: Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) sensor.
Recommended special tools and equipment
- V.A.G 1526 multimeter or V.A.G 1715 multimeter
- V.A.G 1594 connector test kit
- Wiring diagram
Test requirements
- The respective fuses of Mass Air Flow (MAF) Sensor -G70- must be OK.
- Fuel Pump (FP) Relay -J17- must be OK, check.
- Battery voltage must be at least 11.5 volts.
- All electrical consumers such as: lights and rear window defroster must be switched off.
- Parking brake must be engaged or else day time driving lights will be switched on.
- If vehicle is equipped with an A/C system, it must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
- For vehicles with automatic transmission, selector lever must be in -P-.
- Coolant temperature must be at least 80 degrees C. Diagnostic mode 1: Check measured values; PID 5, Coolant temperature. Diagnostic Mode 1: Check Measured Values
Function test
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Start engine and let run at idle.
- Under address word 33, select "Diagnostic mode 1: Check measured values."
- Select the measuring value "PID 16: Air flow quantity at Mass Air Flow (MAF) sensor".
- Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor 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:
- Check voltage supply of Mass Air Flow (MAF) sensor.
If specified value is not obtained:
- Check signal and Ground (GND) wires of Mass Air Flow (MAF) sensor.
Voltage supply of Mass Air Flow (MAF) sensor, checking
- Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor 2 -G70- (arrow).
- Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.
- Start engine, and let run at idle.
Specified value: at least 11.0 V
- Switch ignition off.
If there is no voltage:
- Check wire between 5-pin connector terminal 2 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 Ohms
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If voltage supply and wires are OK:
- Switch ignition on.
- Connect multimeter to terminal 4 of connector and engine Ground (GND) for voltage measurement.
- Switch ignition on.
Specified value: at least 4.5 V
If there is no voltage:
- Switch ignition off.
- Check signal and Ground (GND) wires of Mass Air Flow (MAF) sensor.
Checking signal and Ground wires of Mass Air Flow (MAF) Sensor
- Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor 2 -G70- (arrow).
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test
- Check wires between test box and 5-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Terminal 3 + socket 27
Terminal 4 + socket 53
Terminal 5 + socket 29
Wire resistance: max. 1.5 Ohms
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: Infinite Ohms
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If no DTCs are found in wires:
- Replace Mass Air Flow (MAF) Sensor -G70-. 2
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes