Diagnostic Method 3

Change STFT (A/F compensation value) by interruption, and measure the reaction time of λ value. When A/F sensor malfunctions, the reaction time takes longer than at normal condition. In this case, judge as abnormal.

Fig 1: A/F Sensor Malfunctions Timing Mode Pattern

Courtesy of SUBARU OF AMERICA, INC.

Measure reaction time (t1, t2, t3) and reaction time (t4, t5, t6). Use the average value of the reaction time to obtain the diagnostic value.

Fig 2: Sensor Output Reaction Timing Mode Pattern

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

Time Needed for Diagnosis:  4500 ms

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