Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture LEMARK "LLB555" - Not availableBMW - 3 (E91, E92), 5 (E39, F10, WB), 1, 6, X5, X3, Z4, 7, X6, X1