how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical issues.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the front and rear oxygen sensors from the exhaust system if they are faulty.
  • Use the O2 sensor socket for removal.
  • Inspect the threads and connectors for damage.
• Install new O2 sensors and tighten them to manufacturer specifications (typically 30-40 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Remove any heat shields and unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  • If necessary, use the exhaust hanger removal tool to detach hangers without damaging them.
• Inspect the old catalytic converter for signs of damage or blockage.
• Install the new catalytic converter, ensuring all bolts are tightened to the specified torque (consult the service manual for exact values).

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals securely.
• Use the OBD-II scanner to clear any stored trouble codes from the ECM.