DIAGNOSIS DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To accurately diagnose deterioration and malfunction of an HC adsorbing catalyst, in a diagnosis device for an internal combustion engine with a purifying catalyst installed in an exhaust pipe for the internal combustion engine and the HC adsorbing catalyst installed in series thereto downstream thereof. SOLUTION: The diagnosis device for the internal combustion engine comprises the purifying catalyst installed in the exhaust pipe for the internal combustion engine and the HC adsorbing catalyst installed downstream of the purifying catalyst for adsorbing HC during a low temperature operation and desorbing and purifying it during a high temperature operation. The diagnosis device diagnoses the deterioration of the HC adsorbing catalyst in accordance with a temperature gradient with the temperature of the HC adsorbing catalyst being 50-250 deg.C.