How to Remove the Oxygen Sensor in a Subaru

Written by thomas west
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How to Remove the Oxygen Sensor in a Subaru
A new oxygen sensor can make your Subaru run smoother. (subaru wrx sti image by Jorge Moro from

Subaru is a Japanese company that has been making durable all-wheel-drive vehicles since the 1960s and is still producing cars and sport-utility vehicles as of 2010. The oxygen sensor in your Subaru detects the amount of oxygen in the engine's exhaust. This information is sent to the engine computer module so that the fuel injection system can supply your engine with the proper air to fuel ratio. The heat from your exhaust system will eventually cause the oxygen sensor to fail. The old sensor will need to be removed before a new one can be installed.

Skill level:

Things you need

  • Penetrating fluid
  • Adjustable wrench

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  1. 1

    Park your Subaru on a firm level surface and apply the parking brake. If the car has been driven for several miles recently, allow the engine to cool down completely before beginning work.

  2. 2

    Open the bonnet.

  3. 3

    Locate the oxygen sensor on the catalytic converter which is at the rear of the engine bay near the centre.

  4. 4

    Remove the wiring connector from the sensor by pulling it out by hand. Push the wiring to one side.

  5. 5

    Spray some penetrating fluid onto the sensor fitting and allow it to soak in for a few minutes.

  6. 6

    Remove the sensor with an adjustable wrench turned in a counterclockwise direction.

Tips and warnings

  • Install a new oxygen sensor in the reverse order of the above steps. Apply a thread locker to the threads of the new sensor before installing it. This will ensure it does not loosen from engine vibrations, and will be easy to remove for future replacement. Use a torque wrench on the new sensor and tighten it to 30 foot pounds. If the oxygen sensor is not tight enough in the fitting, your engine may run lean which could make it stumble upon acceleration.
  • Compare the new oxygen sensor to the old one before installing it. Make sure the new sensor is the correct part, as most auto parts store will not accept returns on electrical parts if they have been installed.
  • A faulty oxygen sensor may cause your Subaru to use fuel more excessively. The engine may be hard to start, or may not start at all if the sensor has completely failed.

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