Patent ID: 6382015
Filing Date: 2002-05-07
Classification: F02D,G01N

Abstract:
An apparatus for detecting a resistance of an air-fuel ratio sensor comprising:an oxygen concentration detecting element, a current flowing through the oxygen concentration detecting element being proportional to an oxygen concentration of a detection object gas flowing over the oxygen concentration detecting element; a heater for activating the oxygen concentration detecting element; an air-fuel ratio detector that detects the current flowing through the oxygen concentration detecting element by applying a first voltage to the oxygen concentration detecting element, the air-fuel ratio detector detecting an air-fuel ratio of the detection object gas based on the detected current; the first voltage being a DC voltage; a gas condition detector that detects a condition of the detection object gas; an impedance detector that detects an impedance of the oxygen concentration detecting element by applying a second voltage to the oxygen concentration detecting element, wherein the second voltage is obtained by superimposing an AC voltage on the first voltage; correction means for correcting the impedance detected by the impedance detector, in accordance with the gas condition; and a controller that controls the electrification of the heater based on the impedance corrected by the correction means.