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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, safety goggles, and gloves.
• Allow the vehicle to cool down completely before starting work.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust manifold and catalytic converter.
  4. Install new oxygen sensors by reversing the removal process, ensuring they are torqued to manufacturer's specifications (typically 30 lb-ft).
  5. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove the exhaust pipes connected to the catalytic converter using a socket set.
  2. Inspect the catalytic converter for internal damage or excessive clogging.
  3. If replacement is required, install the new catalytic converter, ensuring proper alignment and sealing.
  4. Torque the connection bolts to manufacturer's specifications (generally around 40-50 lb-ft).
  5. Reattach any exhaust hangers and pipes that were removed.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Start the vehicle and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.