how can I fix the P0420 code on my Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety while working.
• Raise the vehicle using a jack and secure with jack stands for better access to the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the pre-catalytic converter oxygen sensor:
  • Disconnect the electrical connector.
  • Use the O2 sensor socket to unscrew the sensor.
• Install the new oxygen sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Screw the sensor in and torque to manufacturer specifications (typically around 30 ft-lbs).
  • Reconnect the electrical connector.
• Repeat the same procedure for the post-catalytic converter oxygen sensor if it was found faulty during diagnostics.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Remove the exhaust pipe connected to the catalytic converter:
  • Use a socket set to unbolt the flanges.
  • Carefully remove the old catalytic converter.
• Install the new catalytic converter:
  • Ensure the mating surfaces are clean.
  • Use a new exhaust gasket when connecting.
  • Torque the bolts to manufacturer specifications.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it warm up.
• Take the vehicle for a test drive to ensure the check engine light does not reappear and the vehicle operates smoothly.