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

Solution

1. Preparation

• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, multimeter
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Using the O2 sensor socket, carefully remove both sensors.
  3. Inspect the threads and connectors for damage.
  4. Replace any faulty oxygen sensors with OEM parts, ensuring proper torque (typically 30 lb-ft).
  5. Reconnect the battery terminal.

3. Examine and Replace Catalytic Converter (if necessary)

• Tools Required: Wrench set, jack and jack stands, exhaust cutting tool (if needed)
• Sub-steps:
  1. Raise the vehicle using a jack and secure with jack stands.
  2. Inspect the catalytic converter for any signs of physical damage or excessive heat.
  3. If damaged, remove the exhaust bolts securing the catalytic converter to the exhaust system.
  4. If necessary, cut the exhaust pipes using an exhaust cutting tool.
  5. Install the new catalytic converter, ensuring all gaskets are replaced and secured with new bolts.
  6. Lower the vehicle and reconnect the exhaust system.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and allow it to reach operating temperature.
  4. Conduct a test drive to ensure the check engine light does not reappear.