Deterioration detector for exhaust gas sensor and method of detecting deterioration

A deterioration detector for an exhaust gas sensor that is mounted on an exhaust pipe of an internal combustion engine for an automobile and is provided so as to control a temperature control of said exhaust gas sensor by an electric heater thereby detecting deterioration of the exhaust gas sensor comprising:

• initial internal resistance correlation learning storage means for sequentially sampling, comparing, computing and storing an initial internal resistance of said exhaust gas sensor and said electric heater, as well as learning and storing a correlation between the initial internal resistance of said exhaust gas sensor and the initial internal resistance of said electric heater;
• data collection period judgment means for determining a period of sampling said initial internal resistance of said exhaust gas sensor and said electric heater;
• and
• abnormal condition judgment means for computing and storing a current internal resistance of said exhaust gas sensor and said electric heater after a predetermined period of time of an operation start of said internal combustion engine for an automobile, for judging that said current internal resistance of said exhaust gas sensor or said electric heater is less than or greater than predetermined permissible values by comparing said current internal resistance of said exhaust gas sensor and said electric heater with said initial internal resistance of said exhaust gas sensor and said electric heater, respectively, thereby conducting a processing for an abnormal condition.