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Air Fuel Ratio Sensor

 Shop Air Fuel Ratio Sensor

Replacing Your Air-Fuel Ratio Sensor in Three Easy Steps

The air-fuel ratio (AFR) sensor, also known as a mass airflow sensor, gives your vehicle's engine control unit (ECU) the information it needs to accurately maintain the ideal mixture of air and fuel for attaining complete combustion. This precise and fast-acting process results in optimal fuel efficiency and significantly lower emissions. When this sensor fails, you not only lose the benefits, you also experience problems like engine misfires, stalling, or difficulty starting your car. Spare yourself from trouble by replacing this component right away when it malfunctions. If you need to install or replace an AFR sensor, here is an easy-to-follow guide to help you out. This should only take a few minutes for an experienced DIYer.

Required skill level: Novice

Needed tools and materials

  • Phillips-head screwdriver
  • New AFR sensor
  • Locating your air-fuel ratio sensor

    Open the hood of your vehicle and locate your AFR sensor. It is small, cylindrical, and has a wire coming from it. You can usually find it on the throttle body at the rear left side of your engine.

    Removing your malfunctioning sensor

    Unplug the sensor's electrical connector by carefully pulling it off. Use your Phillips-head screwdriver to remove the screws securing the sensor. Extract the old sensor and set it aside.

    Installing your new AFR sensor

    Use your Phillips-head screwdriver to secure your new AFR sensor to the throttle body with the same screws you removed earlier (unless they have deteriorated from rust). Restore the electrical connector. Usually this will snap into place.

    Tips and warnings

    • Make sure your engine has cooled over a number of hours before attempting this procedure.
    • Bear in mind that the AFR sensor is a rather delicate component that can be damaged during installation.
    • This guide was written for a 2001 Toyota Camry. The instructions may be slightly different for other vehicles.