Patent Document ID: 20020060150
Application ID: 09858721
Patent Flag: 0

Claim One:
1. 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 arranged so as to control a temperature 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; data collection period judgment means for determining a period of sampling said initial internal resistance; 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 has varied greatly over a predetermined permissible value by comparing said current internal resistance with said initial internal resistance, thereby conducting a processing for the abnormal condition.