| 摘要 |
A sensor impedance measuring apparatus is provided which is designed to apply one of an alternating voltage swept in level to a positive and a negative side to a sensor element of a gas sensor such as an O<SUB>2 </SUB>sensor or an A/F sensor and sample the voltage developed at an end of the sensor element to determine the impedance of the sensor element. The determined impedance is, for example, used to control energization of a heater built in or affixed to the sensor element to control the activation of the sensor element for ensuring the accuracy in measuring the concentration of a gas.
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