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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical issues.
• Ensure the vehicle is on a flat surface and use wheel chocks for safety.

2. Inspect and Replace O2 Sensors (if necessary)

1. Locate the upstream (pre-catalytic) O2 sensor and the downstream (post-catalytic) O2 sensor.
2. Disconnect the wiring harness from both sensors.
3. Use an O2 sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
4. Compare the new sensors with the old ones to ensure proper fitment.
5. Install the new O2 sensors, tightening them to the manufacturer's specifications (usually around 30-40 lb-ft).
6. Reconnect the wiring harness to both O2 sensors.

3. Replace Catalytic Converter (if necessary)

1. If the catalytic converter is deemed faulty, disconnect the exhaust pipe at both ends of the catalytic converter.
2. Remove any mounting brackets or bolts securing the catalytic converter.
3. Carefully remove the old catalytic converter from the vehicle.
4. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
5. Secure the catalytic converter with new gaskets and bolts, torquing them to manufacturer specifications (commonly around 25-30 lb-ft).
6. Reattach any brackets and exhaust components that were removed.

4. Reconnect Battery and Clear Codes

1. Reconnect the vehicle's battery terminals, ensuring a tight connection.
2. Use an OBD-II scanner to clear the P0420 code from the vehicle's memory.
3. Start the engine and allow it to reach operating temperature.