Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Blue Print "ADM57002C" - Not availableBMW - 3, 5, 1, 6, 7; AUDI - A4, A3; MAZDA - MX-5 (NA); ALFA ROMEO - 159, 156