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Home >> Subaru >> 2021 >> WRX STI >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Fuel Injection System (2.5L) >> Rear Oxygen Sensor >> Installation
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Rear Oxygen Sensor: Installation

CAUTION: If lubricant is spilt onto the exhaust pipe, wipe it off completely with cloth to avoid emission of smoke or causing a fire.
  1. Before installing rear oxygen sensor, apply the anti-seize compound only to the threaded portion of rear oxygen sensor to make the next removal easier.
    CAUTION: Never apply anti-seize compound to the protector of rear oxygen sensor.

    Anti-seize compound: 

    NEVER-SEEZ NSN, JET LUBE SS-30 or equivalent

  2. Install the rear oxygen sensor.

    Tightening torque: 

    21 N.m (2.1 kgf-m, 15.5 ft-lb)

    G08538823Courtesy of SUBARU OF AMERICA, INC.
  3. Connect the connector to the rear oxygen sensor, and hold the rear oxygen sensor harness with the clip (A).
    G08538822Courtesy of SUBARU OF AMERICA, INC.
  4. Install the transmission under cover.

    Tightening torque: 

    18 N.m (1.8 kgf-m, 13.3 ft-lb)

  5. Lower the vehicle.
  6. Connect the battery ground terminal.