| 摘要 |
PURPOSE:To prevent the deterioration in an exhaust cleaning performance, by detecting abnormality in the oxygen concentration detection in accordance with one of air/fuel ratio correction value and a voltage between the electrode pair of a battery element. CONSTITUTION:A voltage VS between electrodes 17a and 17b of a battery element 19 is alternatively supplied from an A/D converter 39, a pump current IP flowing through an oxygen pump element 18, from an A/D converter 40 and the information of throttle valve opening, absolute pressure in an intake tube and cooling water temperature, from an A/D converter 43. Upon the end of the activation of an oxygen concentration sensor, a CPU 47 reads the voltage VS between the electrodes 17a and 17b of the battery element 19 to determine whether the voltage value is OV or not. When VS=OV, it reads the pump current value IP to determine whether the current value IP is above the upper limit value. When the current value IP is above the value, a short-circuiting is judged as occuring between the electrodes 17a and 17b. When the current value IP is below the upper value or equal thereto and also an air/fuel ratio correction value is above the upper limit value, a short-circuiting is judged as occuring between the electrodes 17a and 17b, too.
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