Control apparatus and control method for internal-combustion engine

A control apparatus for an internal-combustion engine, comprising:

• a forward and reverse rotation determining unit which determines whether a crankshaft of the internal-combustion engine is rotated in a forward direction or a reverse direction;
• a stop position detecting unit which detects a crank angle at a time of stopping the internal-combustion engine on the basis of the determination of a rotating direction by the forward and reverse rotation determining unit;
• a diagnosing unit which compares a crank angle estimated on the basis of the crank angle at the time of stopping the internal-combustion engine detected by the stop position detecting unit and a crank angle detected after the internal-combustion engine is started to thereby determine whether the forward and reverse rotation determining unit is abnormal or not;
• an idle reduction control unit which automatically stops the internal-combustion engine in a case in which a preset stop condition is established and which automatically restarts the internal-combustion engine in a case in which a preset restart condition is established;
• and
• a control prohibiting unit which prohibits the idle reduction control unit from automatically stopping the internal-combustion engine on the basis of the crank angle which is estimated on the basis of the crank angle at the time of stopping the internal-combustion engine in a case in which the diagnosing unit determines that the forward and reverse rotation determining unit is abnormal.