Oxygen Sensor Heating Element - (Audi 4000CS Quattro)
- With engine cold, disconnect oxygen sensor heater connection. Connect ohmmeter between male terminals of sensor connector. Start and idle engine. Resistance should be 2-4 ohms. If resistance is incorrect replace oxygen sensor.
- Connect voltmeter between terminals of oxygen sensor female connector. Battery voltage should be present. If not, check continuity of wiring using wiring diagram as a reference.