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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Needed: O2 sensor socket, ratchet, and extension.
• Instructions:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Using the O2 sensor socket, remove the sensors from the exhaust system.
  4. Install the new oxygen sensors by threading them into the exhaust and tightening them to manufacturer specifications (typically 30 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

• Tools Needed: Socket set, torque wrench, gasket scraper.
• Instructions:
  1. Locate the catalytic converter in the exhaust system.
  2. Remove the exhaust heat shield if present, using the socket set.
  3. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  4. Inspect the old catalytic converter for blockages or damage. If damaged, replace it with a new unit.
  5. Install the new catalytic converter, ensuring proper alignment, and torque the bolts to manufacturer specifications (consult repair manual for exact values).
  6. Reinstall the exhaust heat shield if removed.

4. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer system.