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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is on a level surface and secure it with wheel chocks and jack stands.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace O2 Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) O2 sensors.
2. Using an O2 sensor socket, carefully remove the faulty O2 sensors.
3. Install the new O2 sensors and torque them to the manufacturer's specifications (typically around 30 ft-lbs).
4. Reconnect the electrical connectors for the O2 sensors.

3. Inspect and Replace the Catalytic Converter

1. If the O2 sensors are functioning correctly, inspect the catalytic converter for blockages.
2. If blockages are present, remove the catalytic converter by loosening the clamps and bolts securing it to the exhaust system.
3. Clean the exhaust pipes leading to the catalytic converter.
4. Install the new catalytic converter, ensuring all gaskets are replaced and torqued to specifications (usually 30-40 ft-lbs).
5. Reconnect any exhaust clamps or brackets that were removed.

4. Clear the Codes

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
3. Start the engine and allow it to reach operating temperature.