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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the vehicle's battery to ensure safety.
• Ensure the engine is cool before starting work.

2. Inspect and Repair Exhaust System

• Tools Required: Socket set, torque wrench
• Inspect the exhaust system for any leaks or damage.
• Tighten or replace clamps/bolts as necessary.
• If leaks are found, repair or replace affected sections of the exhaust.

3. Replace Oxygen Sensors (if required)

• Tools Required: O2 sensor socket, ratchet
• Locate the upstream and downstream oxygen sensors.
• Disconnect the electrical connectors from both sensors.
• Use the O2 sensor socket to unscrew the sensors from their respective locations.
• Install the new oxygen sensors, ensuring proper torque (typically 30-40 lb-ft).
• Reconnect the electrical connectors to the sensors.

4. Replace Catalytic Converter (if required)

• Tools Required: Socket set, jack and jack stands
• Remove any heat shields or brackets securing the catalytic converter.
• Unbolt the catalytic converter from the exhaust manifold and the mid-pipe.
• Replace with a new catalytic converter, ensuring it matches OEM specifications.
• Torque bolts to the manufacturer's specification (refer to service manual for exact torque value).

5. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use an OBD-II scanner to clear any stored codes.
• Start the vehicle and allow it to reach operating temperature.