Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture LRT "L0198B550" - Not availableCITROËN - C5, C4, Jumpy, C8, Xsara; PEUGEOT - 407, 307; FIAT - Ducato, Ulysse