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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to avoid electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust pipe.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an O2 sensor socket to remove the sensors from the exhaust pipe.
  4. Install new oxygen sensors, ensuring they are torqued to manufacturer specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. If the oxygen sensors are functioning properly, inspect the catalytic converter for blockages or physical damage.
  2. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  3. Remove any mounting brackets securing the catalytic converter.
  4. Replace with a new catalytic converter, ensuring proper alignment and fit.
  5. Reattach all exhaust components and tighten to manufacturer specifications.

4. Reset the Engine Control Module (ECM)

• Sub-steps:
  1. Reconnect the vehicle's battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Start the engine and let it idle for a few minutes to ensure proper operation.