Your ECU monitors the engine's air-fuel ratio thanks to the 2012 Toyota RAV4 O2 sensor which can let the computer know when something is off. A bad sensor won't do this,risking damage to important parts like the catalytic converter,and it can lower gas mileage. A new sensor can get your car back to performing its best by correctly monitoring for lean and rich mixtures so the engine can run as efficiently as possible. Shop 2012 RAV4 oxygen sensors and get free next day delivery or same day pick up at your local store.