Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture DRiV "OPH011" - Not availableCITROËN - C5, C4, Berlingo, C3, C8; AUDI - A4, A6; SAAB - 9-3; ALFA ROMEO - 156, 166