Patent ID: 6966218

Claim:
An apparatus for determining leakage in an evaporated fuel processing system, the evaporated fuel processing system extending from a fuel tank through a canister to a purge passage through which evaporated fuel from the fuel tank is purged to an intake manifold of an engine, the canister comprising a vent-shut valve that communicates with the atmosphere, the apparatus comprising: a pressure sensor for detecting a pressure of the evaporated fuel processing system; a control unit connected to the pressure sensor, the control unit configured to: detect a stop of the engine; close the vent-shut valve to close the evaporated fuel processing system after the stop of the engine is detected; determine whether the evaporated fuel processing system has leakage after the evaporated fuel processing system is closed based on the detected pressure and a predetermined determination value; and prohibit the leakage determination if the detected pressure is not within a predetermined range, wherein the predetermined range is based on a pressure range within which the vent-shut valve can open.