JPH0615853B

PURPOSE:To improve the extent of control accuracy, by calibrating an oxygen sensor at the time of an EGR valve being fully closed, with the detected value, in case of a device which controls a desired EGR rate for feedback on the basis of a detection value of the oxygen sensor installed at the downstream of an opening of an EGR passage in a suction system. CONSTITUTION:Each detection value out of an engine speed detector 8, a suction pipe pressure detector 10, the oxygen sensor 17 installed at the downstream of an opening of an EGR passage 11 in a suction pipe 2 and an opening detector 13 of an EGR control valve 12 is inputted into an EGR control circuit 18. This circuit 18 sets a desired EGR rate on the basis of suction air quantity and engine speed, and controls opening of the EGR control valve 12 for feedback so as to become the oxygen content conformed to this desired EGR rate. In the driving state that the EGR control valve 12 is fully closed such as idleness or the like, a blow-by gas passage 22 is fully closed, finding the detected value of the oxygen sensor 17 at that time, and calibration for the oxygen sensor 17 is carried out on the basis of this value.