2004 Audi A6 Sedan (4B2) V6-2.7L Turbo (BEL) Vehicle > Powertrain Management > Computers and Control Systems > Testing and Inspection > Component Tests and General Diagnostics > Component Tests > Mass Air Flow (MAF) Sensor -G70-, Checking > With Generic Scan Tool MASS AIR FLOW (MAF) SENSOR, CHECKING - BOSCH 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 - VAG1526 multimeter or VAG1715 multimeter - VAG1594 connector test kit - Wiring diagram Test requirements https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 1/8
- The respective fuses of Mass Air Flow (MAF) Sensor -G70- must be OK. - Fuel Pump (FP) Relay -J17- must be OK. - Battery voltage must be at least 11.5 volts. - All electrical consumers like, for example, 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 degree C, Diagnostic mode 1: Check measuring values; PID 5, Coolant temperature. See: Computers and Control Systems > Scan Tool Testing and Procedures > Diagnostic Mode 1: Check Measuring Values Function test - Connect diagnostic tester. See: Computers and Control Systems > Reading and Clearing Diagnostic Trouble Codes > Diagnostic Tester, Connecting - Start engine and let run at idle. - Under address word 33, select "Diagnostic mode 1: Checking measuring 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: https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 2/8
- 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. See: Air Flow Meter/Sensor > Component Tests and General Diagnostics > Mass Air Flow (MAF) Sensor, Checking - Hitachi If specified value is not obtained: - Check signal and Ground (GND) wires of Mass Air Flow (MAF) sensor. See: Air Flow Meter/Sensor > Component Tests and General Diagnostics > Mass Air Flow (MAF) Sensor, Checking - Hitachi Voltage Supply For Mass Air Flow (MAF) Sensor, Checking (Bosch MAF Sensor) https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 3/8
- Disconnect connector from Mass Air Flow (MAF) sensor. - Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement. - Operate starter briefly. Specified value: approx.. battery voltage NOTE: Voltage is supplied to Mass Air Flow (MAF) sensor from Fuel Pump (FP) relay. If there is no battery voltage. - Check wire connection from terminal 2 of connector to Fuel Pump (FP) relay via fuse for open circuit and short circuit to Ground (GND), repair if necessary. https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 4/8
- Connect multimeter to terminal 2 and terminal 3 of connector for voltage measurement. - Operate starter briefly. Specified value: approx.. battery voltage NOTE: Ground (GND) from the ECM is present at terminal 3 of connector. If specified value is not obtained, check wire connections. https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 5/8
- Connect multimeter to terminal 3 and terminal 4 of connector for voltage measurement. - Switch ignition on. Specified value: approx.. 5 volts. If specified value is not obtained, check wire connections. Wire Connections For Mass Air Flow (MAF) Sensor, Checking (Bosch MAF Sensor) NOTE: Signal wire is also checked during wire test. - Connect test box to control module wiring harness, connect test box for wiring test. See: Computers and Control Systems > Reading and Clearing Diagnostic Trouble Codes > Test Box, Connecting For Wiring Test https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 6/8
- The following wire connections must be checked for short circuit to B+, Ground (GND) and for open circuit Connector for Mass Air Flow (MAF) Sensor -G70-3 27 4 53 5 29 VAG1598/31 test box terminal Wire resistance: max: 1.5 Ohm - Also check all wires for short circuit to each other. Specified value: Infinite Ohm (no continuity) - If the voltage supply and the wire connection are OK, replace Mass Air Flow (MAF) Sensor -G70-. https://my.alldata.com/repair/#/repair/article/50067/component/621/itype/383/nonstandard/943151 7/8
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