| 摘要 |
A failure of a filter is detected with a higher degree of accuracy. There are provided a filter that is arranged on an exhaust passage of an internal combustion engine for collecting a substance contained in an exhaust gas, a substance amount detection part that is arranged on the exhaust passage at a downstream side of the filter for detecting an amount of substance in the exhaust gas, a flow speed detection part that detects or estimates a flow speed of the exhaust gas which passes through the filter, and a determination part that makes a determination that the filter is in a failure, when the higher the flow speed of the exhaust gas passing through the filter, the larger a ratio of an amount of change in the amount of substance to an amount of change in the flow speed of the exhaust gas becomes.
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