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Home >> Audi >> 1994 >> S4 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Engine Sensors & Switches >> Mass Airflow Sensor >> Checking MAF Sensor Function
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Checking MAF Sensor Function

  1. Disconnect MAF sensor harness connector. See Figure. Using DVOM, switched to 200 ohms range.
  2. Connect multimeter (using VW 1594 connector test kit) to MAF sensor terminals No. 1 and 2. Record resistance value. See Fig 1.
  3. Disconnect test leads from MAF sensor, and "short" the circuit. Display value must equal value recorded in previous step.
  4. If difference is greater than 0.1 ohm. Replace MAF sensor.
  5. Reconnect MAF sensor harness connector. Peel back rubber boot on back of harness connector to expose terminals.
  6. Switch multimeter to 20 Volt range. Connect multimeter to (exposed) terminals No. 1 and 3. See Fig 2. Switch ignition ON. Voltage must be 1.2-1.5 Volts
  7. Start engine and let idle. Voltage must be approximately 2.5 Volts
  8. Increase Engine Speed (RPM) briefly. Voltage must increase to 3.0-5.0 Volts.
  9. All of the specified voltages must be obtained.
  10. If voltages are not correct, replace MAF sensor.
Fig 1: Identifying Mass Airflow Sensor Terminals
G00177358Courtesy of AUDI OF AMERICA, INC.
Fig 2: Showing Mass Airflow Harness Connector With Weather Boot Pulled Back
G00177359Courtesy of AUDI OF AMERICA, INC.
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