how to fix the P0420 code on my Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool completely before starting.

2. Inspect and Clean Oxygen Sensors

• Remove the upstream and downstream oxygen sensors using a socket wrench.
• Inspect the sensors for carbon buildup or damage.
• Clean the sensors with a suitable electrical cleaner or replace them if damaged.
• Reinstall the oxygen sensors, ensuring they are tightened to the manufacturer's specifications (usually 30 lb-ft).

3. Replace Catalytic Converter (if necessary)

• If the catalytic converter is damaged or clogged, remove it by:
  1. Loosening and removing the bolts securing the catalytic converter to the exhaust system.
  2. Detaching any hangers or brackets holding the converter in place.
  3. Carefully removing the old catalytic converter.
• Install the new catalytic converter:
  1. Position the new converter in place.
  2. Secure it with bolts, tightening to the manufacturer's specifications (consult the service manual, typically around 40-50 lb-ft).
  3. Reattach any hangers or brackets.

4. Reconnect Battery

• Reconnect the negative battery terminal securely.

5. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.