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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and secured.
• Disconnect the battery's negative terminal to prevent electrical issues.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• Remove the pre-catalytic oxygen sensor using the O2 sensor socket. If it's stuck, apply penetrating oil and allow it to soak.
• Install the new oxygen sensor, ensuring it is properly torqued to the manufacturer's specifications (typically around 30 lb-ft).
• Repeat for the post-catalytic oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter (if necessary)
• Raise the vehicle using a jack and secure with jack stands.
• Visually inspect the catalytic converter for physical damage; if damaged, proceed to replace it.
• Remove the exhaust flanges or any bolts securing the catalytic converter to the exhaust system.
• If applicable, cut the exhaust pipe using an exhaust pipe cutter.
• Install the new catalytic converter, ensuring proper alignment with exhaust flanges.
• Tighten all bolts to the manufacturer's torque specifications.

4. Clear Codes and Test Drive

• Reconnect the battery's negative terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the vehicle and let it idle for a few minutes.
• Test drive the vehicle under various conditions to ensure the repair was successful.