Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture LEMARK "LLB1018" - Not availableBMW - 3 (E46, WB), 1, 5 (E39, WB), 6, X5; AUDI - A4, A5; ALFA ROMEO - 147, 156