O2 Sensor Heating Element

To check O2 sensor heating element, disconnect O2 sensor heating element connector from harness connector. Connect voltmeter between harness connector terminals No. 1 and 2. See Fig 1 .
Turn ignition on. Voltmeter should read 12 volts. If voltmeter does not read as specified, repair break in wiring. Connect ohmmeter between terminals No. 1 and 2 of O2 sensor heating element connector. See Fig 2 .
Ohmmeter should read 3-15 ohms. If not, replace O2 sensor.

Fig 1: Identifying O2 Sensor & Differential Pressure Regulator Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

Fig 2: Identifying O2 Sensor Heating Element Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

NOTE: On CIS Motronic system, testing procedures for relays, solenoids, motors and modules are not available.