2015 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE

Front Oxygen (A/F) 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 front oxygen (A/F) sensor, apply anti-seize compound only to the threaded portion of front oxygen (A/F) sensor to make the next removal easier.
    CAUTION: Never apply anti-seize compound to the protector of front oxygen (A/F) sensor.

    Anti-seize compound:Β 

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

  2. Install the front oxygen (A/F) sensor.

    Tightening torque:Β 

    30 N.m (3.1 kgf-m, 22.1 ft-lb)Β 

    Fig 1: Locating Front Oxygen (A/F) Sensor
    G08538815Courtesy of SUBARU OF AMERICA, INC.
  3. Install the under cover. <Ref. to INSTALLATION , Front Under Cover.>
  4. Lower the vehicle.
  5. Secure the front oxygen (A/F) sensor harness to the engine harness stay using the clips (A).
    Fig 2: Identifying Front Oxygen (A/F) Sensor Harness Clips
    G08538814Courtesy of SUBARU OF AMERICA, INC.
  6. Connect the connector to the front oxygen (A/F) sensor, and secure the return hose and front oxygen (A/F) sensor harness using the clip (A).
    Fig 3: Locating Front Oxygen (A/F) Sensor Connector
    G10264866Courtesy of SUBARU OF AMERICA, INC.
  7. Connect the battery ground terminal.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.