Mazda Rear Oxygen Sensor LF5G-18-861 234-4118 Upgrade Replacement Part

When your Mazda shows check engine light, rough idle, abnormal fuel consumption, or exhaust emissions exceedances, it is likely the rear oxygen sensor aged or failed. This sensor monitors oxygen content after the catalytic converter and feeds back to the ECU to precisely adjust the air-fuel ratio for efficient operation and compliant emissions. Upgrade replacement parts with OEM numbers 234-4118, 2344118, LF5G-18-861, LF5G-18-861A, LF5G1886 for standard Mazda models. Ensure sensor threads are clean and tighten to specified torque to avoid leakage or thread damage.