Genuine OEM Audi Lambda Probe, part number 021906265AN. This sensor, also known as an oxygen sensor, is installed in the exhaust system to measure the amount of unburned oxygen in the exhaust gases. This data is critical for the engine control unit (ECU) to adjust the fuel-air mixture for optimal combustion, fuel efficiency, and emissions control. Genuine OEM ensures precise calibration and reliable performance for accurate engine management. The part is located in the exhaust system.