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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical short circuits.
• Ensure the vehicle is on a level surface and safely supported with jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the sensors:
   • Use an O2 sensor socket or wrench.
   • Disconnect the electrical connector for each sensor.
3. Inspect the sensors: Check for signs of damage or contamination.
4. Replace if necessary: If either sensor is faulty, install a new sensor, ensuring to use anti-seize compound on the threads.

3. Inspect and Replace Catalytic Converter

1. Check for damage: If the catalytic converter is damaged or clogged, it needs replacement.
2. Remove the old catalytic converter:
   • Loosen and remove any bolts or clamps securing it to the exhaust system.
   • Carefully disconnect the exhaust pipes.
3. Install the new catalytic converter:
   • Position the new catalytic converter in place.
   • Secure it with the appropriate bolts or clamps, ensuring proper alignment.
   • Torque the bolts to the manufacturer’s specifications (typically 25-35 ft-lbs).
4. Reconnect exhaust system: Ensure all connections are tight and secure.

4. Final Checks

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Check for leaks around the exhaust components.