Rear Oxygen Sensor: Removal

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

Fig 1: Identifying Battery Ground Cable
Courtesy of SUBARU OF AMERICA, INC.
Lift up the vehicle.
Remove the transmission under cover.
Disconnect the connector from the rear oxygen sensor, and remove the clip (A) holding the rear oxygen sensor harness.

Fig 2: Locating Rear Oxygen Sensor Connector And Clip
Courtesy of SUBARU OF AMERICA, INC.
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 sensor, wait until exhaust pipe cools, otherwise it will damage the exhaust pipe.

Fig 3: Identifying Rear Oxygen Sensor
Courtesy of SUBARU OF AMERICA, INC.