Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture VEGAZ "ULS-769" - Not availableBMW - 3, 5, 1, 6, 7; AUDI - A4, A3; MAZDA - RX-8 (FE, SE); ALFA ROMEO - 156, 159