how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle securely using jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use the O2 sensor socket to remove the upstream oxygen sensor. Inspect for corrosion or damage.
  3. Install the new upstream oxygen sensor, ensuring it is properly torqued to manufacturer specifications (usually around 30 lb-ft).
  4. Repeat for the downstream oxygen sensor if it appears faulty or has high resistance readings on the multimeter.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, gasket scraper
• Sub-steps:
  1. Check the catalytic converter for any signs of physical damage or blockage.
  2. If the catalytic converter is damaged, use the socket set to remove the exhaust bolts securing the catalytic converter.
  3. Cut the exhaust pipes if necessary to remove the old catalytic converter.
  4. Clean the exhaust flange surfaces using a gasket scraper.
  5. Install the new catalytic converter, ensuring proper alignment and securing it with bolts to the specified torque (check manufacturer specifications).
  6. Reinstall any removed exhaust components.

4. Reconnect Battery and Clear Codes

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.