Rear Oxygen Sensor: Removal

Disconnect the ground terminal from battery sensor. Ref. to BATTERY
Lift up the vehicle.
Remove the under cover. Ref. to REMOVAL , Front Under Cover.
Disconnect the rear oxygen sensor connector.

Fig 1: Front And Rear Oxygen Sensor Connectors And Clip
Courtesy of SUBARU OF AMERICA, INC.
Remove the front mud guard RH. Ref. to REMOVAL , Mud Guard.
Apply spray-type lubricant (004301003) or equivalent 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 2: Identifying Rear Oxygen Sensor

Courtesy of SUBARU OF AMERICA, INC.