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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the engine is cool before starting work.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace O2 Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil (if necessary)
• If O2 sensor output is faulty, follow these sub-steps:
  1. Locate the upstream and downstream O2 sensors.
  2. Use penetrating oil on the sensor threads if rusted.
  3. Disconnect the electrical connector from the sensor.
  4. Use the O2 sensor socket to remove the sensor from the exhaust pipe.
  5. Install the new O2 sensor by threading it into the exhaust pipe by hand, then tighten it to 30 lb-ft using the torque wrench.
  6. Reconnect the electrical connector.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, gaskets, exhaust hanger removal tool
• If the catalytic converter is damaged or clogged, follow these sub-steps:
  1. Inspect the exhaust system for rust or damage.
  2. Remove any exhaust hangers holding the catalytic converter in place using the exhaust hanger removal tool.
  3. Disconnect any bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe using the socket set.
  4. Carefully remove the old catalytic converter.
  5. Place a new catalytic converter in position, ensuring proper alignment with the exhaust system.
  6. Tighten all bolts to the manufacturer’s specifications (typically 25-30 lb-ft).
  7. Reinstall exhaust hangers.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner
• After repairs, follow these sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear any stored diagnostic trouble codes.
  3. Conduct a test drive to monitor performance and check if the check engine light reappears.