Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Delphi "ES21159-12B1" - Not availableBMW - 3 (F30, F80), 5 (E39, WB), 4 (F32, F33, F82), X5, X3, X6, 6, 1, 2