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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative terminal of the battery to prevent electrical issues during repairs.

2. Inspect and Clean Oxygen Sensors

• Remove the upstream and downstream oxygen sensors using an O2 sensor socket.
• Inspect the sensors for any signs of damage or contamination.
• If the sensors are dirty, clean them with a suitable sensor cleaner, or if they are damaged, proceed to replacement.
• Reinstall the sensors, ensuring proper torque specifications (typically around 30 lb-ft).

3. Replace the Catalytic Converter (if necessary)

• Raise the vehicle securely using jack stands.
• Remove any heat shields covering the catalytic converter using a socket set.
• Disconnect the exhaust pipe from the catalytic converter by removing the bolts or clamps.
• Remove the catalytic converter from its mounting points.
• Install the new catalytic converter, ensuring it is properly aligned and secured.
• Reattach the exhaust pipe and heat shields, torquing bolts to the manufacturer's specifications.

4. Clear Error Codes

• Reconnect the negative terminal of the battery.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.

5. Final Inspection

• Start the engine and let it idle for a few minutes.
• Check for any leaks around the exhaust system and listen for unusual noises.