Patent ID: 6907343

Claim:
A system for detecting malfunction of an engine cooling apparatus constituted as a radiator having a communicating passage connected to an internal combustion engine in such a manner that coolant flows in the radiator to be cooled and a thermostat opening/closing the communicating passage, comprising: engine operation parameter obtaining means for obtaining parameters indicating operating conditions of the engine, including at least a temperature of the coolant of the engine; estimated coolant temperature calculating means for calculating an estimated temperature of the coolant after engine starting based on at least the detected coolant temperature at engine starting and a thermal load parameter correlated to rise in the coolant temperature after engine starting from among of the obtained parameters indicating the operating conditions of the engine; engine standing time period detecting means for detecting a standing time period during which the engine was inoperative prior to the starting; threshold value selecting means for comparing the detected standing time period with a predetermined time period and for selecting at least one of a plurality of preset threshold values based on a result of comparison; and malfunction discriminating means for discriminating whether the cooling apparatus has malfunctioned based on the selected threshold value and at least one of the estimated coolant temperature and the detected coolant temperature.