Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture RIDEX "3922L0276" - Not availableBMW - 3 (E91, E92), 1 (E81, E87), 5, 7, X5, 6, X3, X1, X6; CITROËN - DS3, C4