Monitor Description
The ECM uses the diagnosis value to determine catalyst deterioration. If the diagnostic value exceeds the standard value, the ECM determines that there is catalyst degradation, illuminates the MIL, and stores the DTC.
The diagnosis value is calculated based on the catalyst monitor value (CM) which is determined from the amount of change in the air/fuel ratio sensor lambda value and oxygen sensor value, as well as the reaction rate determined during oxygen sensor reaction time.
*: Diagnosis value = CM x(1 + Reaction rate)
MONITOR STRATEGY
| Related DTCs | P0420: Catalyst monitor with sufficient sensor performance for other monitors functional check |
| Required Sensors/Components (Main) | Air/fuel ratio and oxygen sensors |
| Required Sensors/Components (Related) | Intake air temperature sensor, intake air flow meter SUB-ASSY, vacuum sensor, crankshaft position sensor, and E.F.I. water temperature sensor |
| Frequency of Operation | Once per driving cycle |
| Duration | Less than 1 second |
| MIL Operation | 2 operation cycle |
| Sequence of Operation | None |