Evaporative Leak Check Module (ELCM)
Unlike general gasoline engines in which any leakage is diagnosed using negative pressure within the combustion chamber, a motor acts as the main power source in a PHEV vehicle so the negative pressure within the combustion chamber cannot be used constantly. Therefore, an Evaporation Leak Check Module (ELCM) is installed in a PHEV vehicle to diagnose leakage using a vacuum pump. The Evaporation Leak Check Module (ELCM) diagnoses the leakage of evaporating gas and comprises pressure sensor, vacuum pump, orifice, and Change Over Valve (COV). The Evaporation Leak Check Module (ELCM) detects any leakage by measuring the reference pressure 5 hours after the engine is turned off, operating the vacuum pump, and comparing vacuum pressure generated within the fuel tank with the reference pressure.