What does the Mazda P0421 trouble code mean?
1 Answers
Mazda P0421 trouble code indicates that the catalytic converter's efficiency is below the threshold during the warm-up process. The catalytic converter (also known as a catalytic purification converter) is an exhaust purification device that uses a catalyst to convert CO, HC, and NOx in the exhaust into harmless gases. It is generally located before the muffler in the exhaust pipe. This trouble code indicates that the catalytic converter's efficiency is below the set minimum limit before reaching operating temperature. Possible causes include exhaust gas leakage near the exhaust pipe or manifold, failure of the catalytic converter, malfunction of the engine coolant temperature (ECT) sensor, engine misfire or timing lag, excessively dirty engine oil, oxygen sensor failure, or excessively high fuel system pressure. It is recommended to visit a 4S shop for professional inspection and repair. If severely damaged, the catalytic converter may need to be replaced. Vehicles equipped with catalytic converters must never use leaded gasoline. Avoid impacts to the catalytic converter—although the catalyst carrier is designed with a certain level of mechanical strength to withstand vehicle vibrations, it cannot handle excessive loads, as this may damage the catalyst carrier. Avoid prolonged idling to prevent burning out the catalytic converter. Avoid sudden acceleration to prevent overheating of the catalytic converter. Ensure the engine operates normally to maintain optimal exhaust purification efficiency of the catalytic converter.
