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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, jack stands, socket set, torque wrench, safety goggles, gloves.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative terminal of the battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Unplug the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust system.
  4. Install new oxygen sensors and tighten them to the manufacturer's torque specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  1. Use a jack to raise the vehicle and secure it with jack stands.
  2. Inspect the catalytic converter for any physical damage; if damaged, proceed to replacement.
  3. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  4. Remove any mounting bolts or brackets holding the catalytic converter in place.
  5. Install the new catalytic converter, ensuring proper alignment and tightening bolts to manufacturer specifications.
  6. Reconnect the exhaust system securely.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Start the engine and let it reach operational temperature.
  4. Take the vehicle for a test drive under various conditions to ensure the issue is resolved.