Patent ID: 6679110
Filing Date: 2004-01-20
Classification: F01P,F02D,G01K,Y02T

Abstract:
A method for detecting a malfunction of an internal combustion engine thermostat provided in a coolant circulating path, said method comprising the steps of;detecting a first, starting temperature of coolant on the coolant circulating path on the engine side of said thermostat at a location spaced from said thermostat upon engine starting; determining whether said starting temperature is less than an opening temperature of said thermostat; detecting a second engine side coolant temperature at said location spaced from said thermostat during a period in which said thermostat is normally to be closed; and diagnosing, when the first temperature, detected upon starting, is lower than said opening temperature, whether said thermostat has an open-malfunction based on the second engine side coolant temperature.