Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Fispa "90408" - Not availableBMW - 3, 5, 1, 6, 7; AUDI - A4, A3; MAZDA - 6 (GG, GY), 3; ALFA ROMEO - 156, 159