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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace O2 Sensors (if faulty)

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Steps:
  1. Locate the upstream and downstream O2 sensors in the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the faulty sensor(s).
  4. Install the new O2 sensor(s) and torque to manufacturer specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Check and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Steps:
  1. Inspect the catalytic converter for physical damage or blockage.
  2. If faulty, disconnect the exhaust system from the catalytic converter using a socket set.
  3. Remove the old catalytic converter carefully, ensuring not to damage surrounding components.
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Torque all bolts to manufacturer specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the ECU.