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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to prevent electrical shorts.
• Allow the exhaust system to cool to avoid burns.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors of both sensors.
  3. Use an O2 sensor socket to remove the upstream sensor. Then, repeat for the downstream sensor.
  4. Install the new oxygen sensors by threading them into place and tightening them to the manufacturer's specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust hanger removal tool
• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Locate the catalytic converter in the exhaust system.
  3. Remove any exhaust hangers securing the catalytic converter using the exhaust hanger removal tool.
  4. Use a socket set to remove the bolts securing the catalytic converter to the exhaust pipes.
  5. Remove the catalytic converter from the vehicle and inspect for any physical damage or blockage.
  6. Install the new catalytic converter by reversing the removal steps, ensuring proper alignment and securing it with new bolts if required (follow torque specifications).

4. Reset the Engine Control Module (ECM)

• Tools Required: OBD-II scanner
• Sub-steps:
  1. Reconnect the 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.