HELP, my check engine light is on because of a P0420 fault code.
The P0420 code means that the vehicle’s computer has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). This does not necessarily mean that you have to replace the catalytic converter to fix the problem. Replacing the oxygen (O2) sensors may sometimes fix the code because the vehicle’s computer interprets data from the oxygen sensors to determine if the catalytic converter is working properly.
If the catalytic converter is in fact defective, you must replace it with either a factory (OEM) converter or a California Air Resource Board (CARB) approved aftermarket converter. Be sure that the aftermarket converter is the correct part by confirming:
- Year/Make/Model/Engine Size
- Test Group Name or Engine Family Number *
- Manufacturer Part Number
- Executive Order Number
- Converter Location
* Exception: Federally certified vehicles (Non-California) may not have a matching Test Group/Engine Family number listed on the Aftermarket Catalytic Converter Database. So as long as all other criteria matches, the converter should be approved for the application.
If there are no options listed for your vehicle application on the Aftermarket Catalytic Converter Database, an OEM converter is required.
Many mechanic & muffler shops mistakenly install incorrect converters. If you are unsure, feel free to contact us with any questions.
** This information is accurate as of July 2016. For the most up-to-date rules and regulations, please contact the California Air Resource Board.