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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Park the vehicle on a flat surface and set the parking brake.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Remove the wiring connector from both sensors.
  3. Use the O2 sensor socket to remove the upstream sensor first, followed by the downstream sensor.
  4. Install the new sensors by threading them into their respective locations and torque them to the manufacturer's specifications (usually around 30 lb-ft).
  5. Reconnect the wiring connectors to both oxygen sensors.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Sub-steps:
  1. Remove any heat shields or brackets securing the catalytic converter to the vehicle.
  2. Disconnect the exhaust piping from the catalytic converter by removing the bolts or clamps.
  3. Inspect the old catalytic converter for any signs of damage or clogging.
  4. If necessary, replace the catalytic converter with a new unit that meets OEM specifications.
  5. Reconnect the exhaust piping and secure it with bolts or clamps, torquing to specifications.
  6. Reinstall any heat shields or brackets removed during the process.

4. Reset the ECU

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear any trouble codes from the PCM.
  3. Start the engine and allow it to run for a few minutes to ensure the system is functioning properly.