Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture FEBI Bilstein "39146" - Not availablePEUGEOT - 307, 406, 206, 607, 806; CITROËN - C4, Xsara; FIAT - Ducato, Ulysse