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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors in the exhaust system.
2. Use an O2 sensor socket to remove the faulty oxygen sensors.
3. Install new oxygen sensors by threading them into place and tightening them to the manufacturer’s torque specifications (usually around 30 lb-ft).
4. Reconnect the electrical connectors securely.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Remove the exhaust pipes connected to the catalytic converter using a socket set.
2. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
3. Inspect the old catalytic converter for physical damage or clogging.
4. Install the new catalytic converter by reversing the removal steps, ensuring all bolts are torqued to specifications (typically 30-40 lb-ft).
5. Apply exhaust gasket sealant to joints if required.

4. Reconnect Battery and Clear Codes

1. Reconnect the vehicle's battery.
2. Use the OBD-II scanner to clear the P0420 code.
3. Start the engine and let it run for a few minutes to check for any reoccurrence of the code.