Detection Condition

PCM compares values of front and rear HO2S inversions for a predetermined time. PCM monitors number of inversions that rear side performs while middle side inverts for a specified number of times when the following monitoring conditions are met:

Monitoring Conditions

• Engine speed 1090-3090 RPM.
• Calculated load 16-55 percent (minimum calculated load value varies depending on engine speed).
• Vehicle speed 16.4-64.3 MPH.

PCM detects the inversion ratio. If inversion ratio is less than threshold, PCM determines that catalyst system has deteriorated. This is a intermittent monitor (CATALYST). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. DIAGNOSTIC MONITORING TEST RESULTS and PENDING CODE are available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.