Oxygen (O2) Sensor Heating Element

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.

Disconnect O2 sensor heating element connector. See the ELECTRICAL COMPONENT LOCATIONS table. Connect voltmeter between harness connector terminals. Start engine and let idle. If battery voltage is not present, check for faulty circuit breaker, wiring or fuel pump relay.
If battery voltage is present, connect Test Cable (VAG 1315 A/1) to oxygen sensor heating element connector. Run engine at idle. Set ammeter on 10-amp scale. Check amperage at test cable terminals. If 0.5-3.0 amps is present, heating element is okay. If 0.5-3.0 amps is not present, replace oxygen sensor.

Fig 1: Identifying Terminals Of Typical 2-Pin Connector

Courtesy of AUDI OF AMERICA, INC.

NOTE: To check oxygen sensor control function, read individual measuring values in channels 2 and 3. See READING INDIVIDUAL MEASURING VALUES in the TESTS W/CODES article.