DTC P0421: Notes
DTC P0421 [L3 WITH TC] DETECTION CONDITION AND POSSIBLE CAUSE
| DTC P0421 |
Warm up 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 ratio 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 ratio 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 CONDITIONS
- Engine speed:1, 500-3, 250 rpm
- Calculated TWC temperature: above 400°C {752°F}
- LOAD:15-48%
(at engine speed of 2, 000 rpm
)
Diagnostic support note
- This is an intermittent monitor (Catalyst).
- The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
- PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
- DIAGNOSTIC MONITORING TEST RESULTS is available.
- FREEZE FRAME DATA is available.
- The DTC is stored in the PCM memory.
|
| POSSIBLE CAUSE |
- TWC deterioration or malfunction
- Exhaust gas leakage
- Loose front HO2S
- Loose rear HO2S
- PCM malfunction
|