Apparatus and method for diagnosing blow-by gas recirculation system

An apparatus for diagnosing a blow-by gas recirculation system, the apparatus comprising:

• a head portion of an engine configured to form a combustion chamber;
• a head cover positioned on an upper portion of the head portion;
• a crankcase formed on a lower portion of the combustion chamber;
• an intake line through which an intake-air flows to the combustion chamber;
• a breather hose connecting the crankcase and the intake line at an upstream side of a compressor mounted on the intake line;
• a PCV hose connecting the crankcase and a surge tank;
• and
• a controller configured to determine an abnormality of the breather hose based on a modelled crankcase pressure determined from an atmospheric pressure and an intake flow rate introduced through a throttle valve, and a measured crankcase pressure measured from a pressure sensor configured to measure an internal pressure of the crankcase;
• wherein the controller is further configured to exclude the measured crankcase pressure measured by the pressure sensor while an intake flow rate fluctuation condition in which the intake flow rate abruptly changes in a transient period is satisfied, for determining the abnormality of the breather hose.