Patent ID: 8498797

Claim:
A control apparatus for an internal combustion engine, which is employed for a multi-cylinder internal combustion engine that includes a camshaft provided to press engine valves against reaction force of valve springs; a hydraulically-actuated variable valve operating mechanism which changes a valve characteristic of the engine valves by changing a rotational phase of the camshaft relative to a crankshaft; and a valve stop mechanism which stops opening and closing of the engine valve(s) in a part of cylinders, the control apparatus comprising: a control unit that executes a variable valve control that makes an actual value of the valve characteristic match a target value of the valve characteristic by executing a hydraulic pressure control for the variable valve operating mechanism, and the control unit operates the valve stop mechanism so that a reduced-cylinder operation is performed when an engine operating state is in a preset reduced-cylinder operation region, the control unit having a preset hydraulic determination pressure stored therein; and a hydraulic pressure sensor that detects a pressure of the hydraulic fluid supplied to the variable valve operating mechanism, the hydraulic pressure sensor in communication with the control unit; wherein the control unit compares the hydraulic pressure detected by the hydraulic pressure sensor to the preset hydraulic determination pressure and the control unit prohibits the variable valve control if the detected hydraulic pressure is equal to or lower than the preset hydraulic determination pressure only when the engine operating state is in the reduced-cylinder operation region.