1Pretested, precise and high quality oxygen sensor. 2Designed to improve fuel economy while reducing harmful emissions. 3Helps the engine run efficiently in perfect air-gas ratio. 4Improve engine response and performance. 5Fit for 323i 325i X3 X5 E39 E46.Oxygen sensor is an electronic device that measures the proportion of oxygen in the gas or liquid being analyzed. It is positioned in the exhaust pipe and can detect the ratio of air and gasoline. Features: Pretested, precise and high quality oxygen sensor.Designed to improve fuel economy while reducing harmful emissions.Helps the engine run efficiently in perfect air-gas ratio.Improve engine response and performance.Direct replacement for the original one. Easy installation.Fit for 323i 325i X3 X5 E39 E46.Specification: Condition: 100% Brand New Material: Metal + Plastic Color: as picture show Reference Part Number: 1781433050, 11781433075, 11781433940, 11781742050, 234-4672, 234-4683, 2344672, 2344683, SG1108, ES10899, ES10857, 15109, 13477, 250-24611, 250-24392, 0258005109, 025800347Size: as picture shows Package Weight: approx.564g/20oz Fitment: for 323CI 2000 E 46 M 52 L6-2.5L Upstream and Downstream for 323I 1999-2000 E 46 M 52 L6-2.5L Upstream and Downstream for 325CI 2001-2003/03 E 46 M 54 L6-2.5L Upstream and Downstream for 325I 2001-2003/03 E 46