Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Delphi "ES20277-12B1" - Not availableFIAT - Palio, Marea, Bravo, Brava, Barchetta; LANCIA - Lybra, Y; AUDI - A6, A4