Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Mobiletron "OS-B4156P" - Not availableBMW - 3 (E30, EC), 5, Z1, 7, 8; CITROËN - XM, Xantia; FIAT - Punto, Marea