Rear Oxygen Sensor: Removal

Set the vehicle on a lift.
Disconnect the ground cable from the battery.

Fig 1: Connecting Battery Ground Cable
Courtesy of SUBARU OF AMERICA, INC.
Remove the clip fastening the harness and disconnect the rear oxygen (A/F) sensor connector.

Fig 2: Identifying Front Oxygen (A/F) Sensor Connector And Rear Oxygen Sensor Connector
Courtesy of SUBARU OF AMERICA, INC.
Lift up the vehicle.
Remove the under cover.
Apply spray-type lubricant to the threaded portion of rear oxygen sensor, and leave it for one minute or more.
Remove the rear oxygen sensor.

CAUTION: When removing the rear oxygen (A/F) sensor, wait until exhaust pipe cools, because it can damage the exhaust pipe.

Fig 3: Identifying Front Oxygen (A/F) Sensor And Rear Oxygen Sensor

Courtesy of SUBARU OF AMERICA, INC.