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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent any electrical issues during repair.
• Allow the engine to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  • Remove the upstream and downstream oxygen sensors using an O2 sensor socket.
  • Inspect the sensors for damage or contamination.
  • If faulty, replace them with new sensors, ensuring the connectors are secured properly.
• Tools Required: O2 sensor socket, wrench.

3. Inspect and Clean Catalytic Converter

• Sub-steps:
  • Remove the catalytic converter from the exhaust system by unbolting it from the exhaust manifold and the exhaust pipe.
  • Inspect for any cracks, holes, or excessive carbon buildup.
  • If cleanable, use a specialized catalytic converter cleaner and follow the manufacturer's instructions.
  • If damaged, replace the catalytic converter with an OEM or high-quality aftermarket part.
• Tools Required: Socket set, exhaust gasket, penetrating oil (if needed).

4. Reassemble Exhaust System

• Sub-steps:
  • Reinstall the catalytic converter and tighten the bolts to the manufacturer's torque specifications.
  • Reconnect the oxygen sensors and ensure all connections are tight.
  • Reconnect the battery.
• Tools Required: Torque wrench.

5. Clear Codes and Test Drive

• Sub-steps:
  • Use the OBD-II scanner to clear the P0420 code from the system.
  • Start the engine and perform a test drive to ensure the check engine light does not return.
• Tools Required: OBD-II scanner.