DTC P0421: Notes
DTC P0421 DETECTION CONDITION AND POSSIBLE CAUSES
| DTC P0421 |
Warm up catalyst system efficiency below threshold |
| DETECTION CONDITION |
- The PCM monitors the input voltage from the middle HO2S and the rear HO2S output current when the following conditions are met. If the input voltage change is extremely large compared to the output current change, the PCM determines that the catalyst system has deteriorated.
MONITORING CONDITION
- ECT: more than 70 °C {158 °F}
- Catalyst converter temperature: more than 350 °C {662 °F}
- Engine speed: 1, 000-4, 000 RPM
- LOAD: 19-56%
(at engine speed 2, 000 RPM
)
- Time with purge control system does not operate: more than 5 s
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.
- DIAGNOSTIC MONITORING TEST RESULTS is available.
- FREEZE FRAME DATA is available.
- DTC is stored in the PCM memory.
|
| POSSIBLE CAUSE |
- Exhaust gas leakage
- Loose front HO2S
- Loose middle HO2S
- Loose rear HO2S
- TWC deterioration or malfunction
- PCM malfunction
|