how to fix P0420 code on Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the front (upstream) oxygen sensor by:
  1. Disconnecting the electrical connector.
  2. Using the O2 sensor socket to unscrew the sensor.
  3. Install the new oxygen sensor, tightening it to the manufacturer's specified torque (typically 30 ft-lbs).
  4. Reconnect the electrical connector.
• Repeat the process for the rear (downstream) oxygen sensor if necessary.

3. Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if applicable)
• Lift the vehicle securely using jack stands.
• Remove any heat shields or brackets obstructing the catalytic converter.
• Disconnect the exhaust pipes using a socket set.
• If the catalytic converter is welded in place, carefully cut it out using an exhaust pipe cutter.
• Install the new catalytic converter by reversing the removal steps:
  1. Fit it into place and secure it to the exhaust system.
  2. Tighten all bolts to the manufacturer's torque specifications.
  3. Reinstall any heat shields or brackets.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Test drive the vehicle to monitor engine performance and ensure the check engine light does not reappear.