Page 229 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey
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General Motors Corporation                  21 1





                                  upstream oxygen
                                  sensor (long lean
                                  excursions)









                                  sensor (rich bias
                                  short excursions)





                                  downstream
                                  oxygen sensor
                                  (efficient
                                  converter)







                                  oxygen sensor
                                 (deteriorated
                                 convetter)
                                                                    time



                                             Fig. 93 (from EP0799984)
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