Mass Air Flow (MAF) Sensor, Checking
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
- A.G 1526 portable 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 heating must be switched off.
- Parking brake must be engaged or else daylight 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.
- Coolant temperature must be at least 80 degrees C, Diagnostic mode 1: Check measuring values; PID 5, Coolant temperature. Diagnostic Mode 1: Check Measuring Values
Function test
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Start engine and let run at idle.
- Under address word 33, select "Diagnostic mode 1: Checking 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:
- Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor at idle.
Specified value: 1.80 to 5.60 g/sec
- 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 for Mass Air Flow (MAF) sensor, checking
Vehicles with engine code AEB
- Disconnect 4-pin connector -1- from Mass Air Flow (MAF) sensor -2-.
- Connect multimeter to terminals 1 + 3 of connector for voltage measurement.
- Switch ignition on.
Specified value: at least 11.5 V
- Switch ignition off.
If there is no voltage:
- Check wire connection from terminal 3 to Fuel Pump (FP) Relay -J17- according to wiring diagram.
- Check signal and ground wires
Vehicles with engine code ATW, AUG, AWM
- Disconnect 5-pin connector -1- from Mass Air Flow (MAF) sensor -2-.
- Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.
- Start engine, and let run at idle.
Specified value: 11 to 15 V
If there is no voltage:
- Switch ignition off.
- Check wire connection from terminal 2 to Fuel Pump (FP) Relay -J17- according to wiring diagram.
If voltage supply and wires are OK:
- Switch ignition on.
- Connect multimeter to terminal 4 of connector and engine Ground (GND) for voltage measurement:
Specified value: 4.5 to 5.5 V
If there is no voltage:
- Switch ignition off.
- Check signal and ground wires
Checking signal and Ground wires of Mass Air Flow (MAF) Sensor
- Connect test box to control module wiring harness, connect test box for wiring test. Engine Control Module ECM) is not connected. Test Box, Connecting For Wiring Test
Vehicles with engine code AEB
- Check wires between test box and 4-pin connector for open circuit according to wiring diagram.
Terminal 4 + socket 13
Terminal 2 + socket 12
Wire resistance: max: 1.5 ohms
Vehicles with engine code ATW, AUG, AWM
- Check wires between test box and 5-pin connector for open circuit according to wiring diagram.
Terminal 5 + socket 29
Terminal 4 + socket 53
Terminal 3 + socket 27
Wire resistance: max: 1.5 ohms
Continued for all vehicles
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: Infinite ohms
If no DTCs are found in wires:
- Replace Mass Air Flow (MAF) Sensor -G70-
- 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