DTC P0420, P0430: Notes
DTC P0420, P0430 (MZI-3.5) DETECTION CONDITION AND POSSIBLE CAUSES
| DTC P0420 |
P0420: Catalyst system efficiency below threshold (RH) |
| DTC P0430 |
P0430: Catalyst system efficiency below threshold (LH) |
| DETECTION CONDITION |
- P0420 indicates right bank catalyst system efficiency is below the acceptable threshold.
- P0430 indicates left bank catalyst system efficiency is below the acceptable threshold.
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| POSSIBLE CAUSE |
- Use of leaded fuel.
- Oil contamination
- Cylinder misfiring.
- Damaged HO2S.
- Malfunctioning CHT sensor.
- Downstream HO2S wires improperly connected.
- Fuel pressure too high.
- Damaged exhaust system pipe.
- Damaged exhaust manifold.
- Damaged muffler/tailpipe ass
NOTE:
- Internal deterioration of a catalytic converter is usually caused by abnormal engine operation front of the catalyst. Events that can produce higher than normal temperatures in the catalyst are particularly suspect, such as misfiring. Incorrect HO2S signal input (e.g., rich/lean signal when engine is operating under rich/lean conditions) can cause an abnormal temperature increase in the catalyst. CHT sensor DTCs can indicate that the thermostat is not operating correctly or that the engine coolant level is not filled to specification, producing above normal operating temperatures.
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