DTC P0420: Notes
DTC P0420 DETECTION CONDITION AND POSSIBLE CAUSES
| DTC P0420 |
Catalyst system efficiency below threshold |
| DETECTION CONDITION |
- The PCM compares the number of front HO2S and rear HO2S inversions for a predetermined time. The PCM monitors the rear HO2S inversion counts when the following conditions are met: The PCM detects inversion ratio. If the inversion ratio is below threshold, the PCM determine that catalyst system has deteriorated.
- The front HO2S inversion counts is as prescribed when the following monitoring conditions are met:
- The accumulated occurrence time of the following monitoring conditions has exceeded the prescribed time limit:
MONITORING CONDITION
- Engine speed 1, 300-3, 000 RPM
- Calculated TWC temperature is above 400 °C {752 °F}
- Calculated load 15-48%
(at engine speed 2, 000 RPM)
Diagnostic support note
- This is an intermittent monitor. (Catalyst)
- MIL illuminates if PCM detects above malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM.
- PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.
- FREEZE FRAME DATA is available.
- DTC is stored in the PCM memory.
- DIAGNOSTIC MONITORING TEST RESULTS is available.
|
| POSSIBLE CAUSE |
- TWC deterioration or malfunction
- Exhaust gas leakage
- Looseness of front HO2S
- Looseness of rear HO2S
- PCM malfunction
|