Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture EFI "301310" - Not availableVOLVO - 740, 940, 240, 760, 780; AUDI - 100, 80; ALFA ROMEO - 33, 164; FIAT - UNO, Tipo