| 摘要 |
The present invention relates to a gas concentration detection apparatus for detecting the concentration of a specific gas component in an exhaust gas emitted from an engine, and forms a deterioration judgment about the gas concentration detection apparatus accurately and immediately. After excess oxygen is discharged by an oxygen pump cell 2, a NOx concentration detection apparatus, judges whether a NOx sensor 1 is activated. If the NOx sensor 1 is not activated yet, an output increase rate Vu(t) of the NOx sensor cell output N during an increase process of the NOx sensor cell output N is acquired. The present invention judges whether the output increase rate Vu(t) is lower than a predetermined reference value Vth1. If the obtained judgment result indicates that Vu(t)<Vth1, the NOx sensor cell 4 is deteriorated. |
