What does the P0405 fault code mean for the Besturn X80?

[DeAurora]

The P0405 fault code reported by the Besturn X80 indicates a low circuit in the Exhaust Gas Recirculation (EGR) Valve Sensor A. Working principle of the EGR valve: The high-pressure gas from the compressor enters the EGR valve and flows through the guide vanes in a spiral pattern. The centrifugal force and gravity separate the lubricating oil from the working gas, which then flows down along the inner wall of the cylinder. The working gas passes through a perforated baffle and is discharged from the central pipe of the EGR valve. The separated lubricating oil accumulates at the bottom of the oil separator and can be periodically drained or automatically returned to the compressor's crankcase via a float valve. Function of the EGR valve: It allows a portion of the exhaust gas to be recirculated back into the engine cylinders for combustion. This small amount of exhaust gas lowers the combustion temperature in the cylinders. Since NOX is generated under high-temperature and oxygen-rich conditions, the EGR valve helps suppress NOX formation, thereby reducing NOX emissions in the exhaust.