Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture VEGAZ "ULS-55" - Not availableBMW - 3, 1 (E81, E87), 5, Z4, 6; MERCEDES-BENZ - CLK, C-Class; AUDI - A4, A3