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Oxygen (O2) Sensor Control

WARNING: This page is about a different car, the 1993 Audi 90 and 1993 Audi 100. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect oxygen sensor connector. Refer to the ELECTRICAL COMPONENT LOCATIONS  table. Measure resistance between engine ground and oxygen sensor connector terminal (component side of connector). If resistance is not infinite, replace oxygen sensor.
  2. If resistance is infinite, set voltmeter on 2 volt DC scale. Turn ignition on. Measure voltage between engine ground and oxygen sensor connector terminal (component side of connector). If 350-450 millivolts are present, oxygen sensor is okay. If 350-450 millivolts are not present, check wiring. If wiring is okay, replace ECU.
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