During the operation of an internal combustion engine, a check is made whether the engine functions in an error-free manner in relation to the engine noise. If not, a current value of a cylinder-specific fuel quantity in a cylinder is determined. A check is made whether a current injected cylinder-specific fuel quantity in one of the cylinders is too low or high to check with respect to a cylinder-specific motor speed N_CYL, by comparing a current value of the cylinder-specific injection quantity in the relevant cylinder with a stored reference value of the cylinder-specific injection quantity of the relevant cylinder at the current operating point. A check with respect to the cylinder-specific motor speeds of one of the cylinders is deactivated, if the current injected cylinder-specific fuel quantity in the relevant cylinder is too low or high to check the relevant cylinder with respect to the cylinder-specific motor speed N_CYL.