Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Blue Print "ADG070138" - Not availableBMW - 3, 5, 1, 6, 7; HYUNDAI - I20, I10; AUDI - A4, A3; ALFA ROMEO - 159, 156