1988 Audi 80 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Component Testing: Potentiometer

  1. Ensure engine is at normal operating temperature. Connect Test Adapter (VW1501 ) between potentiometer and harness. See Fig 1 . Connect multimeter to test adapter connectors 1 and 3. Switch multimeter to DC volts scale and turn on ignition. Reading should be 4.35-5.35 volts.
    Fig 1: Installing Harness Adapter
    G94373Courtesy of AUDI OF AMERICA, INC.
  2. Switch multimeter leads to test connectors 2 and 3. Start engine and let idle. Engine cooling fan must not come on during this test. Reading should be .4-.9 volt. If reading is slightly outside tolerance, correct by adjusting the potentiometer trim screw. If correction is not possible, replace potentiometer.
  3. When replacing potentiometer, do not touch resistance strip or contact whiskers inside potentiometer. Loosely install potentiometer. Connect multimeter to test adapter connectors 2 and 3. Turn on ignition and measure voltage. Reading should be 10-100 mV. Adjust potentiometer to read correctly by turning trim screw.
  4. Pull adjusting slide on Sensor Plate Gauge (VW1348/1 ) up to upper stop. Place gauge centrally on edge of airflow sensor with edge No. 3 pointing toward fuel distributor. See Fig 2 . Push adjusting slide down to stop. Rotate setting screw until base of magnet contacts sensor plate mounting screw.
    Fig 2: Installing Sensor Plate Gauge
    G94374Courtesy of AUDI OF AMERICA, INC.
  5. Pull adjusting slide up to first stop (idle position). Adjust potentiometer set screw to obtain .5-.8 volt.
  6. Remove sensor plate gauge and install intake air boot. Start and run engine until cooling fan has cycled at least once. DO NOT  take voltage readings while engine is running.
  7. Stop engine and turn on ignition. Potentiometer voltage should be .4-.9 volt. If voltage reading is out of range, refer to step 2) for procedure. If you have performed all of these procedures and still cannot obtain correct voltage readings, replace airflow sensor.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.