INTERNAL COMBUSTION ENGINE CONTROL SYSTEM

A control unit controls a combustion state of an internal combustion engine in accordance with a drive torque requested by a driver. The control unit performs a switching control to switch at least a combustion state between lean-burn combustion and stoichiometric combustion. A monitor unit performs torque monitoring to determine abnormality of a request torque, which is requested to the internal combustion engine, and a generated torque of the internal combustion engine based on the request torque and an estimation torque, which is an estimation value of an actual torque of the internal combustion engine. A combustion state determining unit determines whether the combustion state in the control unit is the lean-burn combustion or the stoichiometric combustion. A computing unit computes the estimation torque in accordance with the combustion state determined by the combustion state determining unit.