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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface.
• Connect the OBD-II scanner to clear the existing codes once repairs are done.

2. Inspect and Replace O2 Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  • Disconnect the vehicle’s battery to ensure safety.
  • Locate the upstream and downstream oxygen sensors on the exhaust system.
  • Use the O2 sensor socket to remove the upstream sensor.
  • Inspect the connector for corrosion or damage; clean if necessary.
  • Install the new upstream O2 sensor and torque to manufacturer specifications (typically around 30 lb-ft).
  • Repeat the process for the downstream sensor if deemed faulty.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, torque wrench.
• Parts Required: Replacement catalytic converter.
• Sub-steps:
  • Raise the vehicle using a jack and secure it with jack stands.
  • Locate the catalytic converter in the exhaust system.
  • Remove the bolts connecting the catalytic converter to the exhaust manifold and exhaust pipe.
  • Carefully detach the catalytic converter and inspect the old unit for damage.
  • Install the new catalytic converter, ensuring proper alignment and sealing.
  • Torque the mounting bolts to the manufacturer's specifications (usually around 30-40 lb-ft).

4. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0420 code.
• Reconnect the battery.
• Start the vehicle and conduct a test drive to ensure the check engine light does not reappear.