Diagnostic Method

When the rear oxygen sensor output voltage changes from 0.5 V (rich) to 0.15 V (lean), carry out calculation regarding the response time of the output change from 0.45 V to 0.2 V as diagnostic value. When the rear oxygen sensor output voltage does not change from 0.5 V to 0.5 V to 0.15 V, do not carry out calculation even if the output changes from 0.45 V to 0.2 V.

• Abnormality Judgment 

  Judge NG when the rear oxygen sensor output change response time (diagnostic value) exceeds the threshold value.

  Response time > 2 seconds (threshold value) --> Abnormal

  Judge NG when all of the malfunction criteria below is completed.

• Judgment Value 
  Fig 1: Threshold Value Table (1 Of 2)

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  1. Time Needed for Diagnosis: 

     4 seconds

  2. Malfunction Indicator Light Illumination: 

     Illuminates when malfunction occurs in 2 continuous driving cycles.

• Normality Judgment 

  Judge OK when the rear oxygen sensor output change response time (diagnostic value) is below the threshold value.

  Response time =< 2 seconds (threshold value) --> Normal

  Judge NG when the malfunction criteria below is completed.

• Judgment Value 
  Fig 2: Threshold Value Table (2 Of 2)

  Courtesy of SUBARU OF AMERICA, INC.
  NOTE: Response time is calculated during the deceleration fuel cut in case of abnormal judgment. However, in order to make a normal judgment quickly, diagnosis is performed without deceleration fuel cut.
  Fig 3: General Description Graph

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