Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture FAE "75111" - Not availableBMW - 3, 1 (E81, E87), X1, 5, 6; CITROËN - DS3, C4; MERCEDES-BENZ - C-Class, A-Class