Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture BAPMIC "BACB12-741019" - Not availableBMW - 3, 5, 6, 7 (E65, E66, E67), X5; AUDI - A4, A3; ALFA ROMEO - 156, 159