It is shown by many data and the testing result that the valid method of diagnosis for TWC has been found and the changing law of characteristic parameter is obtained.

• 大量数据和试验结果表明,本文所提出的催化器故障诊断系统是一种有效的诊断催化器故障的方法,找到了催化器发生故障时其特征参数的变化规律。