How to fix the P0420 trouble code?
2 Answers
P0420 trouble code can be resolved by replacing the catalytic converter with a brand new one. This trouble code may appear due to a damaged catalytic converter. The catalytic converter is installed at the front section of the exhaust pipe, and this component is used to purify vehicle exhaust. The catalytic converter is a very important part of a car, and it may fail after prolonged use. There are oxygen sensors both before and after the catalytic converter. The oxygen sensor in front is called the front oxygen sensor, and the one behind is called the rear oxygen sensor. The main function of the front oxygen sensor is to detect the oxygen content in the exhaust, which allows it to send data back to the ECU. The ECU can then adjust the air-fuel ratio based on this data. The rear oxygen sensor can also detect the oxygen content in the exhaust and send the data to the ECU. The ECU can compare the data from the front and rear oxygen sensors. If the data from both sensors is the same, it indicates that the catalytic converter has malfunctioned.
I've encountered the P0420 trouble code several times, which indicates low catalytic converter efficiency and poor exhaust purification. Usually, it's caused by a faulty or inaccurate rear oxygen sensor, or a clogged/aged catalytic converter. Last time my check engine light came on, I first used an OBD scanner to check the data stream and compare the output voltage values of the front and rear sensors. If the difference is too small, the catalytic converter might be ineffective. I tried reseating the sensor connectors and cleaning off dust - sometimes the signal would restore. If the sensors are fine, then you need to inspect the catalytic converter for internal damage, which may require replacement. Costs range from a few hundred to several thousand, especially common in older vehicles. Remember not to delay repairs, as it affects fuel consumption, emission standards, and could even cause annual inspection failure. I recommend checking the exhaust system every six months to prevent leaks or carbon buildup issues.
