Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture INTERMOTOR "64570" - Not availableBMW - 3 (E91, E92), 1, X3, Z4 Roadster, 5; AUDI - A4, A3; ALFA ROMEO - 159, 156