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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to avoid electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, multimeter.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust pipe.
  4. Install new sensors, tightening them to the manufacturer’s specified torque (usually around 30 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, jack and jack stands.
• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Locate the catalytic converter and visually inspect it for damage or clogging.
  3. If replacing, unbolt the catalytic converter from the exhaust system (may require cutting if rusted).
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Torque the bolts to manufacturer specifications (typically around 25-30 lb-ft).

4. Clear Error Codes

• Reconnect the battery and start the engine.
• Use the OBD-II scanner to clear the P0420 code and any other related codes from the system.