[Function]: The automotive oxygen sensor monitors exhaust gas oxygen levels, ensuring optimal fuel-to-air ratio for efficient combustion and reduced emissions. [Compatible with]: Subaru Vehicles - 2016-2020 Crosstrek 2.0 H4, 2014-2020 Forester 2.5 H4, 2012-2020 Impreza 2.0 H4, 2013-2019 Legacy 2.5 H4, 2013-2019 Outback 2.5 H4, 2013-2015 XV Crosstrek 2.0 H4. [Reference Number]: 250-54084, 22641AA610, 22641AA640, 22641AA66A, 22641AA670, 18081, 234-9109, 24851. [Service]: We offer a 18-month warranty to ensure your satisfaction and to enhance your shopping experience. [Convenient to install]: By simply removing the existing lambda sensor and installing the replacement unit, you can enjoy substantial savings compared to dealership rates when you purchase this product.