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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety.
• Allow the engine to cool before working on exhaust components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-cat) and downstream (post-cat) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Remove the old sensors using the O2 sensor socket and wrench.
  4. Install new oxygen sensors and torque them to manufacturer specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack stands, exhaust gasket.
• Sub-steps:
  1. Raise the vehicle securely on jack stands.
  2. Remove any heat shields that obstruct access to the catalytic converter.
  3. Unbolt the catalytic converter from the exhaust manifold and exhaust pipe using the socket set.
  4. Inspect the mounting surfaces for damage and clean if necessary.
  5. Install the new catalytic converter, ensuring proper gasket placement and torquing to specifications.
  6. Reinstall heat shields and any other components removed.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the vehicle battery.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Take the vehicle for a test drive to verify that the check engine light does not re-illuminate.