how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
  • Note the orientation and location of each sensor for reinstallation.
• Install new oxygen sensors and torque them to the manufacturer's specifications (usually around 30 lb-ft).
• Reconnect the electrical connectors to the oxygen sensors.

3. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting torch or saw (if needed), exhaust sealant.
• Remove the exhaust pipes connected to the catalytic converter.
  • Use penetrating oil on bolts if rusted or difficult to remove.
• If the catalytic converter is damaged, cut the exhaust pipe if necessary and remove it.
• Install the new catalytic converter, ensuring proper alignment.
  • Use exhaust sealant on connections to prevent leaks.
• Torque all bolts to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code.
• Ensure all connections are secure.