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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to ensure safety while working on electrical components.
• Ensure the vehicle is parked on a flat surface and secure with wheel chocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor:
  • Locate the upstream O2 sensor (usually before the catalytic converter).
  • Use the O2 sensor socket and ratchet to unscrew the sensor.
  • Inspect the sensor for damage or contamination.
  • Replace with a new sensor if needed (torque to manufacturer specifications).
• Repeat the process for the downstream O2 sensor.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary)
• Remove the catalytic converter:
  • Locate the catalytic converter in the exhaust system.
  • Use a socket set to remove the bolts securing the catalytic converter to the exhaust piping.
  • If applicable, cut the exhaust pipe section to remove the converter.
• Install the new catalytic converter:
  • Position the new catalytic converter in place, ensuring proper alignment.
  • Secure it with bolts and torque them to manufacturer specifications.
  • If a cut was made, ensure proper welding or clamping of the exhaust pipe.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer system.