Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture LEMARK "LLB595" - Not availableCITROËN - Xsara, C4, C8, Saxo, C3; PEUGEOT - 206, 306; FIAT - Ulysse, Ducato