Test Step 3 - (K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT

Fig 1: Probing (K99) O2 Sensor 1/1 Heater Control Circuit In O2 Sensor 1/1 Harness Connector

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (K399) O2 Sensor 2/2 Heater Control circuit in the O2 Sensor 2/2 harness connector.

NOTE:

Make sure the test light is probing the circuit before actuating the Heater Test or a DTC may set and not allow the actuation.

With the scan tool, actuate the O2 Sensor 2/2 Heater Test with the Sensor harness connector still disconnected.

NOTE:

The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery.

Does the test light illuminate accordingly during the actuation?

Yes

Go to Test Step 4 - (Z902) O2 SENSOR 2/2 HEATER GROUND CIRCUIT OPEN

Go to Test Step 5 - (K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT SHORTED TO VOLTAGE