BMW 5 Series 520i Oxygen Sensor 11781742050 0258003477 Precise control of air-fuel ratio

Oxygen sensor for BMW 5 Series 520i (E60/E61 chassis, N52/N53 engines), OEM number 11781742050 (Bosch 0258003477), installed before and after the catalytic converter. It monitors exhaust oxygen content in real time and feeds signals to the ECU to precisely control the air–fuel ratio, optimizing combustion efficiency and emissions. Installation difficulty: medium; labor about 0.5–1 hour; avoid thread damage. If the vehicle shows power loss or emissions are high, check this sensor.