| 摘要 |
A monitoring method of a rear oxygen sensor is provided to determine the malfunction of the rear oxygen sensor by using relation between the time of OSC(Oxide Storage Capacity) of catalyst for a smoke filter device and the response time of the rear oxygen sensor. A monitoring method of a rear oxygen sensor comprises: a first step(S12) for determining whether signals, having lower value than lean decision reference value, are applied from the rear oxygen sensor or not; a third step(S16) for calculating the response time for the approval of the signals having greater value than the reach judgment reference value; a fourth step(S22) for calculating the time of OSC of catalyst; a fifth step(S28) for calculating difference for the failure decision base time of the time of OSC of the catalyst and a smoke filter device; a sixth step(S30) for determining whether the calculated difference is longer than the response time of the rear oxygen sensor or not; and a seventh step(S32,S20) for determining that the rear oxygen sensor is normal in case the sixth step is satisfied and determining the malfunction of the rear oxygen sensor in case the sixth step is not satisfied.
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