Diagnostic Method

Detect the trouble by calculating the time from the beginning of the fuel cut to the beginning of the rear oxygen sensor voltage starting to drop.

Fig 1: Beginning Of The Fuel Cut To The Beginning Of The Rear Oxygen Sensor Voltage Starting To Drop Graph

Courtesy of SUBARU OF AMERICA, INC.

• Abnormality Judgment 

  Judge as NG when the following conditions are established.

  JUDGMENT VALUE CHART
  
  

  Malfunction Criteria	Threshold Value
  Time when rear oxygen sensor voltage changed to 0.5 V after the fuel cut started.	> 4000 ms

  Time Needed for Diagnosis:  10 seconds

  Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

• Normality Judgment 

  Judge as OK and clear the NG if the following conditions are established.

  JUDGMENT VALUE CHART
  
  

  Malfunction Criteria	Threshold Value
  Time when rear oxygen sensor voltage changed to 0.5 V after the fuel cut started.	≤ 4000 ms

  Time Needed for Diagnosis:  10 seconds