Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture ERA "570143" - Not availableCITROËN - Xsara, Xantia, Saxo, ZX, Berlingo; PEUGEOT - 306, 106; FIAT - Fiorino, Scudo