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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool completely before starting the repair.

2. Inspect and Replace Oxygen Sensors

• Tools Required: Oxygen sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Using the oxygen sensor socket, remove the sensors by turning counterclockwise.
  4. Install the new oxygen sensors, ensuring they are tightened to the manufacturer's torque specification (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if required)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Sub-steps:
  1. Locate the catalytic converter and inspect for damage.
  2. Remove the bolts securing the catalytic converter to the exhaust system using the socket set.
  3. Remove exhaust hangers using the exhaust hanger removal tool.
  4. Install the new catalytic converter, aligning it properly with the exhaust system.
  5. Secure it with bolts, tightening them to the specified torque value (usually around 40 ft-lbs).
  6. Reattach the exhaust hangers.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and allow it to reach operating temperature.
  4. Perform a test drive under various conditions to ensure the check engine light does not return.