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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and disconnect its electrical connector.
  2. Use penetrating oil on the threads of the oxygen sensor to ease removal.
  3. Remove the upstream oxygen sensor using the O2 sensor socket.
  4. Install the new upstream oxygen sensor and torque it to manufacturer specifications (usually around 30 lb-ft).
  5. Reconnect the electrical connector to the new sensor.
  6. Repeat the process for the downstream (post-catalytic) oxygen sensor if it tested faulty.

3. Check and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter, gasket scraper.
• Sub-steps:
  1. Verify that the catalytic converter is faulty by checking for blockages or excessive wear.
  2. Lift the vehicle securely using jack stands.
  3. Disconnect the exhaust pipe from the catalytic converter using a socket set.
  4. Remove any bolts or clamps securing the catalytic converter to the exhaust system.
  5. Replace with a new catalytic converter and ensure proper alignment.
  6. Torque bolts to specification (typically around 25 lb-ft for exhaust components).
  7. Reconnect the exhaust pipe and check for leaks.

4. Final Steps

• Reconnect the battery.
• Clear the P0420 code using the OBD-II scanner.
• Perform a test drive to ensure the issue is resolved.