Diagnostic Method

When the three-way catalytic converter performance falls, the oxygen storage capacity performance also falls. A malfunction is detected by a diagnosis that estimates the oxygen storage capacity performance based on the time and air volume required from completion of the deceleration fuel cut for the predetermined time or longer until the start of increase in the rear oxygen sensor voltage.

Time needed for diagnosis:  Less than 1 s

Malfunction indicator light illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.