Detection Condition
WARNING: This page is about a different car, the 2003 Mazda B4000, 2003 Mazda B3000, and 2003 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
- DTC P0420 indicates Bank 1 (right cylinder bank) catalyst system efficiency is less than acceptable threshold.
- DTC P0430 indicates Bank 2 (left cylinder bank) catalyst system efficiency is less than acceptable threshold.
Interior deterioration of catalytic converter is usually caused by abnormal engine operation. Events that produce higher than normal temperatures in the catalyst are particularly suspect (misfires). Incorrect HO2S signal input may cause abnormal temperature increase in the catalyst. ECT sensor DTCs may indicate an incorrectly operating thermostat or coolant level is not to proper level, producing higher than normal operating temperatures.