Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture FEBI Bilstein "24231" - Not availableBMW - 3 (E46, WB), Z3, 7, X5, 5; AUDI - A6, A4; HYUNDAI - Lantra, Accent