第八代索纳塔后氧传感器 39210-2E400，有效降低有害尾气，行车更环保。

8th-generation Hyundai Sonata rear oxygen sensor (OEM 39210-2E400) directly replaces the original, high compatibility. Core function is to monitor exhaust oxygen content and feed back to ECU to precisely control air-fuel ratio, effectively reducing harmful exhaust and improving environmental performance. Installation resolves high fuel consumption, engine vibration, or tailpipe emissions issues; especially suitable before annual inspection. If the dashboard check engine light is on or you feel acceleration is weak or fuel consumption rises, aging sensor is likely; replacement is advised.