It sounds like you have an exhaust leak, or the engine is running poorly, how does the engine run? If okay and the cats and O2 sensor have been replaced the only other thing, is it can be a bad PCM because it has lost the ability to monitor the emission system. Here is the location of the PCM and how to change it out in the images below. You can get a preprogrammed unit by searching Google or Ebay.
Here is generic info on the p0420 code:
Faulty catalytic converter: The catalytic converter may be worn out or damaged, resulting in reduced efficiency. Over time, the catalyst inside the converter can degrade, leading to this error code.
Oxygen sensor issues: The oxygen sensors (both upstream and downstream) play a crucial role in monitoring the efficiency of the catalytic converter. If the downstream oxygen sensor detects minimal or no change in emissions, it can trigger the P0420 code.
Exhaust leaks: Leaks in the exhaust system before the catalytic converter can introduce excess oxygen into the system. This can cause the oxygen sensors to incorrectly detect a low catalytic converter efficiency.
Engine misfire or running rich: A persistent engine misfire or a condition where the engine runs excessively rich (excessive fuel) can lead to an inefficient catalytic converter.
Check out the images (below). Please let us know what happens.
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Thursday, May 25th, 2023 AT 9:56 AM
