how to fix P0420 code in Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery before starting any repairs to avoid electrical issues.

2. Inspect and Replace Oxygen Sensors

1. Locate and Remove Oxygen Sensors
   • Use an O2 sensor socket to carefully remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
   • Disconnect the electrical connectors.
2. Inspect Sensors
   • Check the sensors for signs of contamination or damage. If they are damaged, they should be replaced.
3. Install New Oxygen Sensors
   • Apply anti-seize compound to the threads of the new oxygen sensors.
   • Install the new sensors by threading them into the exhaust pipe and connecting the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the Old Catalytic Converter
   • Use a socket set to unbolt the catalytic converter from the exhaust system. Make sure to support it to prevent it from falling.
2. Inspect Exhaust System
   • Ensure that all flanges and gaskets are in good condition. Replace if necessary.
3. Install New Catalytic Converter
   • Position the new catalytic converter in place and secure it with bolts to the exhaust system. Use a torque wrench to tighten to the manufacturer’s specifications (typically around 30-40 lb-ft).
4. Reconnect Exhaust System
   • Ensure all connections are tight and secure to prevent exhaust leaks.

4. Clear Codes and Test Drive

1. Reconnect Battery
   • Reconnect the negative battery terminal.
2. Clear Error Codes
   • Use the OBD-II scanner to clear the P0420 code from the system.
3. Perform a Test Drive
   • Drive the vehicle under various conditions to ensure that the check engine light does not reappear.