Diagnostic Method

When enable conditions are completed, measure the A/F sensor output A/F value variation period by changing air fuel ratio desired value to lean and rich. Judge NG when this period is long. Judge OK when this period is short.

Judge NG when the malfunction criteria below is completed. Judge OK when the malfunction criteria below is not completed.

Judgment Value 

Fig 1: Threshold Value Table

Courtesy of SUBARU OF AMERICA, INC.

Map 5 

Fig 2: Engine Speed Table

Courtesy of SUBARU OF AMERICA, INC.

1. Time Needed for Diagnosis: 

   2 to 12 seconds

2. Malfunction Indicator Light Illumination: 

   Illuminates when malfunction occurs in 2 continuous driving cycles.